Internet-Draft URN LEX Namespace for Sources of Law December 2023
Spinosa, et al. Expires 17 June 2024 [Page]
Network Working Group
Intended Status:
P. Spinosa
E. Francesconi
Consiglio Nazionale delle Ricerche (CNR)
C. Lupo

A Uniform Resource Name (URN) Namespace for Sources of Law (LEX)


This document describes a Uniform Resource Name (URN) Namespace Identification (NID) convention for identifying, naming, assigning, and managing persistent resources in the legal domain. This specification is published to allow adoption of a common convention by multiple jurisdictions to facilitate ease of reference and access to resources in the legal domain.
This specification is an independent submission to the RFC series. It is not a standard, and does not have the consensus of the IETF.

Status of This Memo

This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.

Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at

Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."

This Internet-Draft will expire on 17 June 2024.

Table of Contents

1. Introduction

1.1. The Purpose of Namespace "lex"

The purpose of the "lex" namespace is to assign a unique identifier, in well-defined format, to documents that are sources of law. To the extent of this namespace, "sources of law" include any legal document within the domain of legislation, case law and administrative acts or regulations; moreover potential "sources of law" (acts under the process of law formation, as bills) are included as well. Therefore "legal doctrine" is explicitly not covered.

The identifier is conceived so that its construction depends only on the characteristics (details) of the document itself and, therefore, it is independent from the document on-line availability, its physical location, and access mode. The identifier itself is assigned by the jurisdiction of the identified document. Even a document that is not available online may, nevertheless, have a LEX URN identifier.

Such an identifier can be used as a way to represent references (and more generally, any type of relation) among various sources of law. In an on-line environment with resources distributed among different Web publishers, identifiers, in terms of uniform resource names, allow a simplified global interconnection of legal documents by means of automated hypertext linking. LEX URNs consist of persistent and location-independent identifiers and are particularly useful when they can be mapped into or associated with locators such as HTTP URLs. Moreover, LEX URNs details can be used as a reference to create HTTP-based persistent and location-independent identifiers [RFC3986]. Such kind of identifiers have been suggested within the set of principles and technologies, known as "Linked Data", as a basic infrastructure of the semantic web to enable data sharing and reuse on a massive scale.

1.2. Community Considerations

The use of the "lex" namespace facilitates the interoperability of information systems used in the Public Administration at the national and international level. Moreover it allows the distribution of the legal information towards a federated architecture. In such an architecture, documents are directly managed by the issuing authorities, with resulting benefits in information authenticity, quality and currency. A shared identification mechanism of resources guarantees that a distributed system will be as efficient and effective as a comparable centralized system.

Creators of Internet content that references legal materials - including publishers operating well outside the traditional arenas of legal publishing - benefit by the registration of the namespace because it facilitates the linking of legal documents, whether by manual or automated means, and reduces the cost of maintaining documents that contain such references.

Any citizen or organisation with Internet web browser capability will have the possibility to use the namespace and its associated application, registers, and resolution services, to facilitate document access (if available).

LEX URNs also identify offline resources, for instance by making it easier for organizations such as legislative bodies, law libraries, and legal publishers to identify resources and generate links between such resources (e.g., for the purpose of stable citation).

1.3. Background

This specification of a unique identifier for legal documents follows a number of initiatives in the field of legal document management.

Since 2001 the Italian Government, through the National Center for Information Technology in the Public Administration, the Ministry of Justice and CNR (the National Research Council of Italy) promoted the NormeInRete project. It was aimed at introducing standards for sources of law description and identification using XML and URN techniques.

Other national initiatives in Europe introduced standards for the description of legal sources [FRAN]. Collaborations between government, national research institutes, and universities, have defined national XML standards for legal document management, as well as schemes for legal document identification. Outside of Europe, similar initiatives have addressed similar problems [FRAN]. Several of these identifiers are based on a URN schema.

In today's information society the processes of political, social and economic integration of European Union member states as well as the increasing integration of the world-wide legal and economic processes are causing a growing interest in exchanging legal information knowledge at national and trans-national levels. The growing desire for improved quality and accessibility of legal information amplifies the need for interoperability among legal information systems across national boundaries. A common well-defined schema used to identify sources of law at international level is an essential prerequisite for interoperability.

Interest groups within several countries have already expressed their intention to adopt a shared solution based on a URN technique.
The need for a unique identifier of sources of law in different EU Member States, based on open standards and able to provide advanced modalities of document hyper-linking, has been expressed in several conferences (as [LVI]) by representatives of the Publications Office of the European Union (OP), with the aim of promoting interoperability among national and European institution information systems. Similar concerns have been raised by international groups concerned with free access to legal information, and the Permanent Bureau of the Hague Conference on Private International Law [HCPIL] that encourage State Parties to "adopt neutral methods of citation of their legal materials, including methods that are medium-neutral, provider-neutral and internationally consistent.". In a similar direction the CEN Metalex initiative is moving, at European level, towards the definition of a standard interchange format for sources of law, including recommendations for defining naming conventions to them.

The need of unique identifiers for sources of law is of particular interest also in the domain of case law. This is acutely felt within both common law systems, where cases are the main law sources, and civil law systems, in order to provide an integrated access to cases and legislation, as well as to track the relationships between them. This domain is characterized by a high degree of fragmentation in case law information systems, which usually lack interoperability.

In the European Union, the community institutions have stressed the need for citizens, businesses, lawyers, prosecutors and judges to become more aware not only of (directly applicable) EU law, but also of the various national legal systems. The growing importance of national judiciaries for the application of Community law was stressed in the resolution of the European Parliament of 9 July 2008 on the role of the national judge in the European judicial system.
Similarly the the Council of the European Union has underlined the importance of cross-border access to national case law, as well as the need for its standardisation, in view of an integrated access in a decentralized architecture. In this view the Working Party on Legal Data Processing (e-Law) of the Council of the European Union formed a task group to study the possibilities for improving cross-border access to national case law. Taking notice of the report of the Working Party's task group the Council of the EU decided in 2009 to elaborate on a uniform, European system for the identification of case law (ECLI: European Case-Law Identifier) and uniform Dublin Core-based set of metadata.

The Council of the European Union invited the Member States to introduce in the legal information systems the European Legislation Identifier (ELI), an http-based Semantic Web oriented identification system for European Union and Member States legislation.

The LEX identifier (also referred in this text as "LEX name") is conceived to be general enough so as to provide guidance at the core of the standard and sufficient flexibility to cover a wide variety of needs for identifying all the legal documents of different nature, namely legislative, case-law and administrative acts. Moreover, it can be effectively used within a federative environment where different publishers (public and private) can provide their own items of a legal document (that is there is more than one manifestation of the same legal document).

Specifications and syntax rules of LEX identifier can be used also for http-based naming convention to cope with different requirements in legal information management, for example the need of having an identifier compliant with the Linked Open Data principles.

This document supplements the required name syntax with a naming convention that interprets all these recommendations into an original solution for sources of law identification.

The following entities support the publication of this proposal:

  • CNR (National Research Council of Italy) - Italy;

  • Agency for Digital Italy (AgID) - Presidency of the Council of Ministers - Italy;

  • PRODASEN - IT Department of the Federal Senate - Brazil;

  • LII (Legal Information Institute), Cornell Law School - USA.

1.4. General Characteristics of the System

The specifications in this document promote interoperability among legal information systems by defining a namespace convention and structure that will create and manage identifiers for legal documents. The identifiers are intended to be:

  • globally unique

  • transparent

  • reversible

  • persistent

  • location-independent, and

  • language-neutral.

These qualities facilitate legal document management and a mechanism of stable cross-collections and cross-country references.

Transparency means that given an act and its relevant metadata (issuing authority, type of measure, etc.), it is possible to create the related URN that is able to uniquely identify the related act in a manner that is reversible (from an act to its URN and from a URN to the related act).

Language-neutrality is an especially important feature that promotes adoption of the standard by organizations that must adhere to official-language requirements. This specification provides guidance to both public and private groups that create, promulgate, and publish legal documents. Registrants wish to minimize the potential for creating conflicting proprietary schemes, while preserving sufficient flexibility to allow for diverse document types and to respect the need for local control of collections by an equally diverse assortment of administrative entities.

The challenge is to provide the right amount guidance at the core of the specification while providing sufficient flexibility to cover a wide variety of needs. LEX does this by splitting the identifier into parts. The first part uses a pre- existing standard specification ("country/jurisdiction name standard") to indicate the country (or more generally the jurisdiction) of origin for the legal document being identified; the remainder ("local name") is intended for local use in identifying documents issued in that country or jurisdiction.

The second part depends only on the system of sources of law identification operating in that nation and it is mainly composed by formalized information related to the enacting authority, the type of measure, the details and possibly the annex.

The identification system based on uniform names includes:

  • a schema for assigning names capable of representing unambiguously any addressed source of law (namely legislation, case law and administrative acts), issued by any authority (intergovernmental, supranational, national, regional and local) at any time (past, present and future);

  • a resolution mechanism - in a distributed environment - that ties a uniform name to the on-line location of the corresponding resource(s).

This document considers the first of these requirements. It also contains a few references to the architecture of the resolution service and to the corresponding software.

1.5. Linking a LEX Name to a Document

The LEX name is linked to the document through meta-information which may be specified as follows:

  • within the document itself through a specific element within an XML schema or by an [W3C.HTML] META tag;

  • externally by means of a Resource Description Framework [W3C.rdf-schema] triple, a specific attribute in a database, etc.

At least one of these references is necessary to enable automated construction and update of catalogues (distributed and centralized) and the implementation of resolvers that associate the uniform name of a document with its physical location(s). LEX assumes no particular relationship between the originator of the document, its publisher, and the implementer of catalogues or resolution services.

1.6. Use of LEX Names in References

LEX names can be used in references as an HREF attribute value of the hypertext link to the referred document. This link can be created in two ways:

  • by manually inserting in the referring document the link with the uniform name: this is a burdensome procedure, especially for documents that are already on-line;

  • by automatically constructing (either permanently or temporarily) the link with the uniform name, through reference parsers of a text: this is a more time-saving procedure even if subject to a certain percentage of errors, since references are not always accurate or complete. This solution could nevertheless be acceptable for already published documents.

Whatever method is adopted, new documents produced in whatever format (for example XML, XHTML, etc) should express references through the uniform name of the document referred to.

1.7. Definitions

The following terms are used in these specifications:

  • Source of Law: a general concept to refer to legislation, case law, regulations and administrative acts. In its broadest sense, the source of law is anything that can be conceived as the originator of 'erga omnes' legal rules. In this document "Source of Law" refers also to acts during their making such as bills that might or might not become laws;

  • Jurisdictional Registrar: an organization that shares and defines in any jurisdiction the assignment of the main components of the resource identifier through which the identifier uniqueness is guaranteed.

1.8. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

1.9. Syntax Used in this Document

This document uses the syntax common to many Internet RFCs, which is based on the ABNF (Augmented Backus-Naur Form) [RFC5234] meta- language.

1.10. Namespace Registration

The "lex" namespace has already been registered in the "Formal URN Namespaces" registry.

2. Registration of LEX

2.1. Identifier Structure

The identifier has a hierarchical structure as follows:

   "urn:lex:" NSS

where NSS is the Namespace Specific String composed as follows:

   NSS = jurisdiction ":" local-name


  • jurisdiction identifies the scope (state, regional, municipal, supranational or of an organization) where a set of sources of law have validity. It is also possible to represent international organizations (either states or public administrations or private entities);

  • local-name is the uniform name of the source of law in the country or jurisdiction where it is issued; its internal structure is common to the already adopted schemas. It represents all aspects of an intellectual production, from its initial idea, through its evolution during the time, to its realisation by different means (paper, digital, etc.).

The jurisdiction element is composed of two specific fields:

   jurisdiction = jurisdiction-code *(";" jurisdiction-unit)


  • jurisdiction-code is usually the identification code of the country where the source of law is issued.
    To facilitate the transparency of the name, the jurisdiction-code follows usually the rules of identification of other Internet applications, based on domain name (for details and special cases see Section 2.2).
    Due to the differences in representation in the various languages of a country, for an easier identification of the country the use the standard [ISO3166-1] is strongly RECOMMENDED.
    Therefore a urn-lex ID always begins with a sequence of ASCII characters: "urn:lex:ccTLD". For all the other components that follow the jurisdiction-code, the Jurisdictional Registrar decides the mode of representation (ASCII or UTF-8 %-encoding) (see Section 3.4).
    Where applicable, the domain name of the country or multinational or international organisation is used.
    If such information is not available for a particular institution, a specific code will be defined (see Section 2.2). Examples reported in this document are hypothetical and assume that the corresponding domain name is used for the jurisdiction-code.

  • jurisdiction-unit are the possible administrative hierarchical sub- structures defined by each country or organisation within their specific legal system. This additional information can be used in case two or more levels of legislative or judicial production exist (e.g., federal, state and municipality level) and the same bodies may be present in each jurisdiction. Therefore acts of the same type issued by similar authorities in different areas differ for the jurisdiction-unit specification.
    An example can be the following:
    "br:governo:decreto" (decree of federal government),
    "br;sao.paulo:governo:decreto" (decree of SU+00E3o Paulo state)
    "br;sao.paulo;campinas:governo:decreto" (decree of Campinas

Examples (hypothetical) of sources of law identifiers are:

    (Italian act)
    (French act)
    (Spanish act)
    (Glarus Swiss Canton decree)
    (EU Commission Directive)
    (US SC decision: Riley vs Illinois)
    (Decision of the Belgian Council of State)

2.2. Jurisdiction-code Register

It is planned to create a new registry for jurisdiction-code, with the following format:

  • jurisdiction-code: the identifier of jurisdiction, assigned to the country or organisation;

  • jurisdiction: the official name of the jurisdiction, country or organisation;

  • registrant: essential information to identify the organization that requested the registration of the code. The registrant will be responsible for its DNS zone and for the attribution of sub-zone delegations, and so on. It is RECOMMENDED that each jurisdiction create a registry of all delegated levels so that the organization responsible of each sub-zone can easily be identified;

  • reference: a reference to the defining document (if any).

The table is initially empty. Possible example entries are:

"br"; "Brazil"; "Prodasen, Federal Senate, address, contact";
"eu"; "European Union"; "DG Digit, European Commission, address,
      contact"; \[reference\]
""; "United Nations"; "DPI, United Nations, address,
          contact"; \[reference\]

CNR is responsible for the jurisdiction-code and the root lex-nameserver registries of the resolution routing.

A new Jurisdictional Registrar will contact CNR or the Designated Expert(s) according to the established rules of governance (published in the CNR website dedicated to the LEX governance). The application will be evaluated according to the Jurisdictional Registrar authoritativeness and the offered guarantees. The Designated Expert(s) will evaluate such applications, with a similar approach as of the DNS. Typically such applications should come from public administrations, as authorities enacting sources of law.

The adopted registration policy is similar to that of the "Expert Review" as specified in [RFC8126]. Designated Experts will assign jurisdiction codes based on the following principles:

  • If a request comes from a jurisdiction that corresponds to a country and the jurisdiction code is the same as a top level ccTLD, then the top level ccTLD should be used as the jurisdiction code;

  • If a request comes from a jurisdiction that corresponds to a multi- national (e.g., European Union) or international (e.g., United Nations, World Trade Organization) organizations the Top Level Domain Name (e.g., "eu") or the Domain Name (e.g., "", "") of the organization should be used as the jurisdiction code;

  • in case when such multi-national or international organization does not have a registered domain, Designated Expert(s) should assign something like, where name will be the acronym of the organization name, in the language chosen by the organization itself. For example, the jurisdiction code of the European Economic Community could be "". Anyway the alias mechanism allows to have acronyms in different languages.

Jurisdiction codes MUST NOT be renamed, because that would violate rules that URN assignments are persistent.

Jurisdiction codes MUST NOT ever be deleted. They can only be marked as "obsolete", i.e. closed for new assignments within the jurisdiction. Requests to obsolete a jurisdiction code are also processed by Designated Expert.

Designated Expert(s) can unilaterally initiate allocation or obsolescence of a jurisdiction code.

Request for new jurisdiction code assignment must include the organization or country requesting it and Contact information (email) of who requested the assignment.

2.3. Conformance with URN Syntax

The "lex" NID syntax conforms to [RFC8141]. However, a series of characters are reserved to identify elements or sub-elements, or for future extensions of the LEX naming convention (see Section 3.2).

2.4. Validation Mechanism

The Jurisdictional Registrar (or those it delegates) of each adhering country or organization is responsible for the definition or acceptance of the uniform name's primary elements (issuing authority and type of legal measure).

2.5. Scope

Global interest. In fact each body that enacts sources of law can identify them by this scheme. Furthermore, other bodies (even not enacting sources of law, such as newspaper or magazine publishers, etc.) aiming to refer legal documents, can unequivocally identify them by this scheme.

3. General Syntax and Features of the LEX Identifier

This section lists the general features applicable to all jurisdictions.

3.1. Allowed and Not Allowed Characters

These characters are defined in accordance with the [RFC8141] "Uniform Resource Names (URNs)". For various reasons, later explained, in the "lex" NSS only a subset of characters is allowed. All other characters are either eliminated or converted.

For the full syntax of the uniform names in the "lex" space, please see Section 8.

3.2. Reserved Characters

The following characters are reserved in the specific "lex" namespace:

"@" separator of the expression, that contains information on
    version and language;
"$" separator of the manifestation, that contains information on
    format, editor, etc.;
":" separator of the main elements of the name at any entity;
";" separator of level. It identifies the introduction of an element
    at a hierarchically lower level, or the introduction of a
"+" separator of the repetitions of an entire main element (e.g.,
    multiple authorities);
"|" separator between different formats of the same element (e.g.,
"," separator of the repetitions of individual components in the main
    elements, each bearing the same level of specificity (e.g.,
    multiple numbers);
"~" separator of the partition identifier in references (e.g.,
    paragraph of an article);
"*" and "!" are reserved for future expansions.

To keep backward compatibility with existing applications in some jurisdictions, the "lex" NID syntax does not include the use of the character "/" in this version.
This character is always converted into "-", except in the formal annexes (see Section 6.4.1).

3.3. Case Sensitivity

For all the languages where different cases (upper or lower cases) or different spelling of the same word are possible, names belonging to "lex" namespace are case-insensitive. It is RECOMMENDED that, in latin alphabet, they be created in lower case, but names that differ only in case, or in the spelling, of the same word MUST be considered to be equivalent.
(e.g., "Ministry" will be recorded as "ministry").

3.4. Unicode Characters outside the ASCII Range

In order to exploit DNS as a routing tool towards the proper resolution system, to keep editing and communication more simple and to avoid character percent-encoding, it is RECOMMENDED that the characters outside the ASCII range (e.g. national characters, diacritic signs, ...) are turned into base ASCII characters (e.g., the Italian term "sanitU+00E0" replaced into "sanita", the French term "ministU+00E8re" replaced into "ministere"), in case by transliteration (e.g. "MU+00FCnchen" replaced into "muenchen").

This mapping consists of:

  • transcription from non-Latin alphabets;

  • transliteration of some signs (diaeresis, eszett, ...);

  • preservation of the only basic characters, eliminating the signs placed above (accents, tilde, ...), below (cedilla, little tail, ...) or on (oblique cut, ...).

The most suitable, well-known and widespread mapping system for a given language MUST be chosen by the jurisdiction, or, in agreement with this one, by the jurisdiction-unit in case of different languages in the various regions, also taking into account the choices made for the same language by other jurisdictions.
Certainly this mapping is simpler and more feasible for languages that use the Latin alphabet and gradually becomes more complex both for other alphabets and for writing systems with opposite orientation (from right to left) or based on ideographic symbols.

If this conversion is not acceptable by a specific jurisdiction or it is not available in a given language, UNICODE MUST be used and, for accessing network protocols, any UNICODE code points outside the ASCII range MUST be converted in UTF-8 %-encoding according to [RFC3986] and [RFC3629].
In this case it should be noted that the generated URN (as some of its parts) cannot be used directly for routing through DNS, and therefore the jurisdiction must adopt one of the following strategies:

  • to convert non-ASCII characters within the DNS into the IDN encoding, using the [RFC5894] punycode translation (e.g. mU+00FCnchen in xn--mnchen-3ya), and to develop an interface software that converts the URN before the navigation in DNS, or

  • to create a routing service relying on a software, out of DNS, addressing a proper resolution service.

Note that the urn:lex ID, could contain groups of characters (UTF-8 %-encoded) of some languages with different orientations: in this case the BiDi rules apply [RFC5893].

Summarizing, the preference order is the following:

  • Conversion into basic ASCII, RECOMMENDED solution (for not having to make conversions for network protocols and DNS);

  • Using UNICODE, and connvert into UTF-8 %-encoding [RFC3629], for accessing network protocols, and to punycode [RFC5894], only for navigation in DNS, via software interface;

  • Creation of a routing service relying on a software, out of DNS, addressing a proper resolution service.

The first solution allows native DNS routing, while the other two require software development for the interface or the routing. However it is up to the specific jurisdiction to choose the preferred solution.

Two examples (Latin and Cyrillic alphabet) relating to the different solutions adopted are here reported:

a circular adopted by the Municipality of Munich (Rundschreiben der
  Stadt MU+00FCnchen):
- ascii = urn:lex:de:stadt.munchen:rundschreiben:...
- unicode = urn:lex:de:stadt.mU+00FCnchen:rundschreiben:...
- utf-8 = urn:lex:de:stadt.m%xC3%xBCnchen:rundschreiben:...
- punycode = urn:lex:de:stadt.xn--mnchen-3ya:rundschreiben:...
a state law of the Russian Federation (latin: gosudarstvo zakon;
  cyrillic: U+0441U+043EU+0441U+0442U+043EU+044FU+043DU+0438U+0435
- ascii = urn:lex:ru:gosudarstvo:zakon:...
- unicode = urn:lex:ru:U+0441U+043EU+0441U+0442U+043EU+044FU+043D
- utf-8 = urn:lex:ru:%xD1%x81%xD0%xBE%xD1%x81%xD1%x82%xD0%xBE%xD1
- punycode = urn:lex:ru:xn--80aebe3cdmfdkg:xn--80ankme:...

assuming that the Russia jurisdiction-code is expressed
in ASCII ("ru"),
while the Cyrillic version ("U+0440U+0444") has the
puny-code "xn--p1ai".

3.5. Abbreviations

Abbreviations are often used in law for indicating institutions (e.g. Min.), structures (e.g. Dept.), or legal measures (e.g. Reg.) but not in a uniform way, therefore their expansion is highly RECOMMENDED. (e.g., "Min." is reported as "ministry")

3.6. Date Format

The [ISO.8601.1988] is the international format for representing dates: therefore dates MUST always be represented in this format (4 digits for the year, 2 digits for the month, 2 digits for the day):

    date-iso = yyyy-mm-dd

(e.g., "September 2, 99" will be written as "1999-09-02").

This format ensures interoperability between different representation systems and there are several programs for mapping other formats to this one.
However, to make reading and understanding such other formats (e.g. Jewish calendar), the urn:lex scheme provides that the date can be added in the jurisdiction's own format
(e.g. the date in the previous example would be 21.Elul,5759, that is:

- in Hebrew characters:
- in UTF-8 code:

Therefore, for all the dates in the urn:lex identifier (see Section 6.3 and Section 7.1.2), it is also possible to indicate the one in the local format:

    date = date-iso [ "|" date-loc ]

(e.g., "September 2, 99" will be written in ISO plus Hebrew format as
"1999-09-02|U+05DBU+05F4U+05D0.U+05D0U+05B1U+05DCU+05D5U+05BCU+05DC. U+05EAU+05E9U+05E0U+05F4U+05D8").

The characters which are not allowed (e.g. "/") or which are reserved (e.g. ",") cannot exist inside the date-loc and therefore MUST be turned into ".".

4. Specific Syntax and Features of the LEX Identifier

In this section there are other features related to specific jurisdictions and the implementation of which is RECOMMENDED.

4.1. Spaces, Connectives and Punctuation Marks

All the language connectives (e.g., articles, prepositions, etc.), the punctuation marks and all the special characters (as apostrophes, dashes, etc.), when explicitly present, are eliminated (no transformation occurs in cases of languages with declensions or agglutinating languages). The words left are connected to each other by a dot (".") which substitutes the "space".
(e.g., "Ministry of Finances, Budget and of Economic Planning" becomes "ministry.finances.budget.economic.planning";
"Ministerstvo Finansov" becomes "ministerstvo.finansov")

4.2. Acronyms

The use of acronyms might be confusing and encourage ambiguity in uniform names (the same acronym may indicate two different institutions or structures), therefore their expansion is highly RECOMMENDED.
(e.g., "FAO" is expanded as "food.agriculture.organization")

4.3. Ordinal Numbers

To even the representation, it is highly RECOMMENDED that any ordinal number included in a component of a document name (e.g., in the description of an institution body) is indicated in Western Arabic numerals, regardless to the original expression: whether in Roman numerals, or with an adjective, or in Arabic numeral with apex, etc. (IV, third, 1U+00B0, 2^, etc.).
(e.g., "Department IV" becomes "department.4")

5. Creation of the Source of Law LEX Identifier - Baseline structure

5.1. Basic Principles

The uniform name must identify one and only one document (more precisely a "bibliographic resource" [ISBD], see also Section 5.2) and is created in such a way that it is:

  • self-explanatory ;

  • identifiable through simple and clear rules;

  • compatible with the practice commonly used for references;

  • able to be created from references in the text, automatically (by parser) or manually;

  • representative of both the formal and the substantive aspects of the document.

5.2. Model of Sources of Law Representation

According to the [FRBR] (Functional Requirements for Bibliographic Records) model developed by IFLA (International Federation of Library Associations and Institutions), in a source of law, as in any intellectual production, four fundamental entities (or aspects) can be specified.

The first two entities reflect its contents:

  • work: identifies a distinct intellectual creation; in our case, it identifies a source of law both in its original form as amended over time;

  • expression: identifies a specific intellectual realisation of a work; in our case it identifies every different (original or up-to- date) version of the source of law over time and/or language in which the text is expressed.

The other two entities relate to its form:

  • manifestation: identifies a physical embodiment of an expression of a work; in our case it identifies embodiments in different media (printing, digital, etc.), encoding formats (XML, PDF, etc.), or other publishing characteristics;

  • item: identifies a specific copy of a manifestation; in our case it identifies individual physical copies as they are found in particular physical locations.

In this document the [FRBR] model has been interpreted for the specific characteristics of the legal domain. In particular, apart from the language that does produce a specific expression, the discriminative criterion between expression and manifestation is based on the difference of the juridical effects that a variation can provide with respect to the involved actors (citizens, parties, institutions). In this scenario the main characteristic of the expression of an act is represented by its validity over the time, during which it provides the same juridical effects. These effects may change as a result of amendments or annulments of other legislative or jurisprudential acts. Therefore notes, summarizations, comments, anonymizations and other editorial activities over the same text do not produce different expressions, but different manifestations.

5.3. The Structure of the Local Name

The local-name within the "lex" namespace MUST contain all the necessary pieces of information enabling the unequivocal identification of a legal document. If the local-name violates this requirement, the related URN is not a valid one within the "lex" namespace.

In the legal domain, at "work" level, three components are always present: the enacting authority, the type of provision and the details. A fourth component, the annex, can be added if any. It is often necessary to differentiate various expressions, that is:

  • the original version and all the amended versions of the same document;

  • the versions of the text expressed in the different official languages of the state or organization.

Finally the uniform name allows a distinction among diverse manifestations, which may be produced by multiple publishers using different means and formats.

In every case, the basic identifier of the source of law (work) remains the same, but information is added regarding the specific version under consideration (expression); similarly a suffix is added to the expression for representing the characteristics of the publication (manifestation).

Information that forms a source of law uniform name at each level (work, expression, manifestation) is expressed in the official language of the relevant jurisdiction; in case of multiple official languages (as in Switzerland) or more involved jurisdictions (as in international treaties), more language-dependent names (aliases) are created.

Therefore, the more general structure of the local name appears as follows:

       local-name = work ["@" expression] ["$" manifestation]

However, consistent with legislative practice, the uniform name of the main original provision (work) becomes the identifier of an entire class of documents which includes: the original main document, the annexes, and all their versions, languages and formats subsequently generated.

5.4. Structure of the Document Identifier at "Work" Level

The structure of the document identifier is comprised of the four fundamental elements mentioned above, distinguished one from the other ordered by increasingly narrow domains and competencies:

   work = authority ":" measure ":" details *(":" annex)


  • authority is the issuing or proposing authority of the measure (e.g., State, Ministry, Municipality, Court, etc.);

  • measure is the type of the measure, both public nature (e.g., constitution, act, treaty, regulation, decree, decision, etc.) as well as private one (e.g., license, agreement, etc);

  • details are the terms associated to the measure, typically the date (usually the signature date) and the number included in the heading of the act;

  • annex is the identifier of the annex, if any (e.g., Annex 1).

In case of annexes, both the main document and its annexes have their own uniform name so that they can individually be referenced; the identifier of the annex adds a suffix to that of the main document. In similar way the identifier of an annex of an annex adds an ending to that of the annex which it is attached to.

The main elements of the work name are generally divided into several elementary components, and for each component, specific rules of representation are established (criteria, modalities, syntax and order). For the details regarding each element, please see the Section 6. Examples (hypothetical) of work identifiers are:


The type of measure is important to identify case law, as well as legislation, especially within the legal systems where cases are identified traditionally only through the year of release and a number. Since the aim of the lex schema is to identify specific materials, the type of measure or the full date are able to differentiate between materials belonging to a specific case.

Here below is an example where the type of measure or the full date are essential for identify specific materials of a case:

- 4/59 Judgment of the EEC Court of Justice 04/04/1960, Mannesmann
  AG and others / ECSC High Authority;4-59
- 4/59 Order of the EEC Court of Justice 18/05/1960, Mannesmann AG
  and others / ECSC High Authority;4-59

5.5. Aliases

International treaties involve multiple signatory jurisdictions, and are therefore represented through multiple identifiers, each of them related to a signatory. For example, a bilateral France and Germany treaty is identified through two URNs (aliases) belonging to either "fr" or "de" jurisdiction
(e.g., "urn:lex:fr:etat:traite:..." and "urn:lex:de:staat:vertrag:...") since it pertains to both the French and the German jurisdiction.

In the states or organisations that have multiple official languages, a document has multiple identifiers, each of them expressed in a different official language, basically a set of equivalent aliases. This system permits manual or automated construction of the uniform name of the referred source of law in the same language used in the document itself.
(e.g., "urn:lex:eu:council:directive:2004-12-07;31", "urn:lex:eu:consiglio:direttiva:2004-12-07;31", etc.)

Moreover, a document can be assigned more than one uniform name in order to facilitate its linking from other documents. This option can be used for documents that, although unique, are commonly referenced from different perspectives. For example, the form of a document's promulgation and its specific content (e.g., a Regulation promulgated through a Decree of the President of the Republic).

5.6. Structure of the Document Identifier at "Expression" Level

There may be several expressions of a legal text, connected to specific versions or languages.

Each version is characterized by the period of time during which that text is to be considered to be in force or effective. The lifetime of a version ends with the issuing of the subsequent version. New versions of a text may be brought into existence by:

  • amendments due to the issuing of other legal acts and to the subsequent production of updated or consolidated texts;

  • correction of publication errors (rectification or errata corrige);

  • entry into or departure from a particular time span, depending on the specific date in which different partitions of a text come into force.

Each such version may be expressed in more than one language, with each language-version having its own specific identifier. The identifier of a source of law expression adds such information to the work identifier, using the following main structure:

    expression = version [":" language]


  • version is the identifier of the version of the original or amended source of law. In general it is expressed by the promulgation date of the amending act; other specific information can be used for particular documents. If necessary, the original version is specified by the string "original", expressed in the language of the act or version (for the details regarding this element, please see the Section 7);

  • language is the identification code of the language in which the document is expressed, according to [RFC5646] (it=Italian, fr=French, de=German, etc.). The granularity level of the language (for example the specification of the German language as used in Switzerland rather than the standard German) is left to each specific jurisdiction. The information is not necessary when the text is expressed in the sole official language of the country or jurisdiction.

Hypothetical examples of document identifiers for expressions are:

    (original version in French)
    (original version in German)
    (amended version in French)
    (amended version in German)
    (original version in French of a Belgian decision)

5.7. Structure of the Document Identifier at "Manifestation" Level

To identify a specific manifestation, the uniform name of the expression is followed by a suitable suffix containing the following main elements:

  • editor: editorial staff who produced it, expressed according to its Internet domain name. Since publishers' domain names may vary over time, manifestations already assigned by a publisher remain unchanged even if the identified object is no longer accessible. In this case, in order to make its materials accessible, the publisher will have to create for each of them a new manifestation with the new domain name;

  • format: the digital format (e.g., XML, HTML, PDF, etc.) expressed according to the MIME Content-Type standard [RFC2045], where the "/" character is to be substituted by the "-" sign;

  • component: possible components of the expressions contained in the manifestation. Such components are expressed by language- dependent labels representing the whole document (in English "all") or the main part of the document (in English "body") or the caption label of the component itself (e.g. Table 1, Figure 2, etc.);

  • feature: other features of the document (e.g., anonymized decision text).

The manifestation suffix thus reads:

    manifestation = editor ":" format
                    [":" component [":" feature]]

To indicate possible features or peculiarities, each main element of the manifestation MAY be followed by further specifications (separated by ";"), for example as regards editor the archive name and the electronic publisher, for format the version, etc. Therefore the main elements of the manifestation will assume the forms:

    editor = publisher *(";" specification)
    format = mime *(";" specification)
    component = part *(";" specification)
    feature = attribute *(";" specification)

The syntax details of the manifestation element is shown in Section 8, in the related part.

(examples (hypothetical):

the original version of the Italian act 3 April 2000, n. 56 might have the following manifestations with their relative uniform names:

- PDF format (vers. 1.7) of the whole act edited by the Italian
- XML format (version 2.2 DTD NIR) of the text of the act and PDF
  format (version 1.7) of the "Figura 1" (figure 1) contained in the
  body, edited by the Italian Senate:

the Spanish URN of the html format of the whole Judgment of the European Court of Justice n. 33/08 of 11/06/2009, in Spanish version, published in the Jurifast database in anonymized form:


It is useful to be able to assign a uniform name to a manifestation (or to a part of it) in case non-textual objects are involved. These may be multimedia objects that are non-textual in their own right (e.g. geographic maps, photographs, etc.), or texts recorded in non-textual formats, such as image scans of documents.

5.8. Sources of Law References

References to sources of law often refer to specific partitions of the act (article, paragraph, etc.) and not to the entire document.

From a legal point of view, a partition is always a text block, that represents a logical subdivision of an act.

As regards the digital representation, a partition is represented by an element (a block of text) with its own ID; this ID aims to identify the related element and to locate it. In this case, therefore, it is possible either to extract or to point to a partition.

In a mark-up not fitting the logical structure of the text (as HTML), generally only the starting point of the partition, rather than the whole block of text or element, is identified through a label (a <a id=partitionID></a> tag in Html Markup Language [W3C.HTML]). In this case therefore it is not possible to extract a partition but only to point to it.

Partitions should be assigned unique labels or IDs within the including document and their value should be the same regardless of document format.

For enabling the construction of the partition identifier between different collections of documents, specific construction rules for IDs or labels will be defined and shared, within each country or jurisdiction, for any document type
(e.g., for legislation, the paragraph 2 of the article 3 might have as label or ID the value "art3;par2", similarly for case-law, paragraph 22 of the judgment in Case 46/76 Bauhuis v Netherlands, might have as label or ID the value "par22").

Furthermore, it is useful to foresee the compatibility with applications able to manage this information (e.g., returning the proper element); these procedures are particularly useful in the case of rather long acts, such as codes, constitutions, regulations, etc. For this purpose it is necessary that the partition identifier is transmitted to the servers (resolution and application) and therefore it cannot be separated by the typical "#" character of URI fragment, which is not transmitted to the server.

According to these requirements, the syntax of a reference is:

     URN-reference = URN-document ["~" partition-id]

(e.g., to refer to the paragraph 3 of the article 15 of the French Act of 15 May 2004, n. 106, the reference can be "urn:lex:fr:etat:loi:2004-05-15;106~art15;par3").

Using a different separator ("~") from the document name, the partition ID is not withheld by the browser but it is transmitted to the resolution process. This enables the resolver to retrieve (for example, out of a database) only the referred partition, if the partition syntax is compatible with the media type used, otherwise to return the whole act.

When resolving to HTTP, the resolver SHALL transform the partition ID to an appropriate internal reference (#) in the page, or at the beginning if that point cannot be found. The transformation in URI fragment is obtained appending to the URL the "#" character followed by the partition ID (in the example above, the returned URL will be <URL-document>#art15;par3). Doing this, knowing the granularity of the act markup, the resolver could exploit the hierarchical structure of the ID, eliminating sub- partitions not addressed. If only the article was identified in the act, in the previous example it could return <URL-document>#art15 only.

It is possible to use the general syntax (with "#"); in this case only the URN document component of the reference is transmitted to the resolver, therefore the whole document will be always retrieved.

6. Specific Syntax of the Identifier at "Work" Level

6.1. The authority Element

6.1.1. Indication of the Authority

The authority element of a uniform name may indicate, in the various cases:

  • the actual authority issuing the legal provision. More specifically, the authority adopting the provision or enacting it;

  • the institution where the provision is registered, known and referenced to, even if produced by others (e.g., the bills identified through the reference to the Chamber where they are presented);

  • the institution regulated (and referred to in citations) by the legal provision even when this is issued by another authority (e.g., the statute of a Body);

  • the entity that proposed the legal material not yet included in the institutional process (e.g. a proposed bill written by a a political party).

6.1.2. Multiple Issuers

Some sources of law are enacted by a number of issuing parties (e.g., inter-ministerial decrees, agreements, etc.). In this case, the authority element contains all the issuing parties (properly separated), as follows:

   authority = issuer *("+" issuer)

(e.g., "ministry.justice+ministry.finances")

6.1.3. Indication of the Issuer

Each issuing authority is essentially represented by either an institutional office (e.g., Prime Minister) or an institution (e.g., Ministry); in the last case, the authority is indicated in accordance with the institution's hierarchical structure, from the more general to more specific (Council, Department, etc.), ending with the relative office (President, Director, etc.). Therefore, the structure of the issuer is as follows:

   issuer = (institution *(";" body-function)) / office

(e.g., "ministry.finances;department.revenues;manager")

6.1.4. Indication of the Body

Depending on the kind of measure, the body within the issuing authority is unambiguously determined (e.g., the Council for Regional Acts) and normally it is not indicated in the references. Just like in practice, the indication of the enacting authority is limited to the minimum in relation to the type of measure.
(e.g., "region.tuscany:act" and not "region.tuscany;council:act")

6.1.5. Indication of the Function

Generally, the function is indicated, sometimes instead of the body itself:

  • in case of political, representative or elective offices
    (e.g., "university.oxford;rector:decree" instead of "university.oxford;rectorship:decree");

  • when it refers to a top officer in the institution (e.g., general manager, general secretary, etc.) which is not always possible to associate a specific internal institutional structure to
    (e.g., "national.council.research;general.manager").

It is not indicated when it clearly corresponds to the person in charge of an institution (typically, a general director); in this case, only the structure and not the person in charge is indicated
(e.g., "ministry.justice;department.penitentiary.administration").

The function MUST be indicated when:

  • it is not the same of the director or the person in charge of the structure (for example, in case of an undersecretary, a deputy director, etc.);

  • the type of measure may be both monocratic or collegial: the indication of the office eliminates the ambiguity.

6.1.6. Conventions for the Authority

Acts and measures bearing the same relevance as an act, issued or enacted since the foundation of the State, have conventionally indicated "state" (expressed in each country official language) as authority; the same convention is used for constitutions, codes (civil, criminal, civil procedure, criminal procedure, etc) and international treaties.

6.2. The measure Element

6.2.1. Criteria for the Indication of the Type of Measure

In uniform names the issuing authority of a document is mandatory. This makes unnecessary to indicate any further qualification of the measure (e.g., ministerial decree, directorial ordinance, etc.), even if it is widely used. When the authority-measure combination clearly identifies a specific document, the type of measure is not defined through attributes referring to the enacting authority.
(e.g., "region.tuscany:act" and not "region.tuscany:regional.act")

6.2.2. Further Specification to the Type of Measure

In the measure element, it is usually sufficient to indicate the type of a measure. As usual, references to sources of law, rather than through the formal details (date and number), may be made through some of their characteristics such as the subject-matter covered (e.g., accounting regulations), nicknames referring to the promoter (e.g., Bassanini Act) or to the topic of the act (e.g., Bankruptcy Law), etc.. In these cases, the type of measure MAY be followed by further specifications useful in referencing even if the details are lacking:

      measure = measure-type *(";" specification)

(e.g., "regulations;accounting" or "act;bankruptcy")

6.2.3. Aliases for Sources of Law with Different Normative References

There are legislative measures that, although unique, are usually cited in different ways, for example through the legislative act introducing them into the legal order (President's decree, legislative decree, etc.) or through their legislative category (regulations, consolidation, etc.). In order to ensure, in all the cases, the validity of the references, an alias (additional URN LEX identifier), that takes into account the measure category, is added to what represents the legislative form of the same act.
(e.g., "state:decree.legislative:1992-07-24;358" and "state:consolidation;public.contracts:1992-07-24;358").

6.2.4. Relations between Measure and Authority in the Aliases

The sources of law including different normative references are usually introduced in legislation through the adoption or the issuing of an act, which they are either included or attached to. It is, therefore, necessary to create an alias linking the two aspects of the same document. Specifically, the different measures can be:

  • adopted/issued by an authority different from the one regulated by the provision (e.g., the statute of a Body); in this case, the correlation is established between two uniform names each featuring a completely different authority element
    (e.g., "italian.society.authors.publishers:statute" and "ministry.cultural.activities+ministry.finances.budget.economic. planning:decree");

  • issued by the institution itself either because it has issuing authority or by virtue of a proxy (e.g., a provision that refers to the functioning of the Body itself); in this case, the two aliases share the first part of the authority;
    (e.g., "municipality.firenze:statute" and "municipality.firenze;council:deliberation");

  • issued by the same Body to regulate a particular sector of its own competence; in this case the authority element is the same
    (e.g., "ministry.justice:regulation; telematic.process" and "ministry.justice:decree").

6.3. The Details Element

6.3.1. Indication of the Details

The details of a source of law usually include the date of the enactment and the identification number (inclusion in the body of laws, register, protocol, etc.).

Some measures can have multiple dates; there are also cases in which the number of the measure does not exist (unnumbered measures) or a measure has multiple numbers (e.g., unified cases). For these reasons, the set up of both elements (date and number) includes multiple values.

Some institutions (e.g., the Parliaments) usually identify documents through their period of reference (e.g., the legislature number) rather than through a date, which would be much less meaningful and never used in references (e.g., Senate bill S.2544 of the XIV legislature). In these cases, the component period is used in substitution of the component dates.

Usually details of a measure are not reported according to a specific sequence; in accordance with the global structure of the uniform name, which goes from the general to the specific, the sequence date-number has the following form:

    details = (dates / period) ";" numbers

(e.g., "2000-12-06;126", "14.legislature;s.2544")

6.3.2. Multiple Dates

Some sources of law, even if unique, are identified by more than one date; in this case, in the field dates all the given dates are to be reported and indicated as follows:

dates = date *("," date)

(e.g., the measure of the Data Protection Authority of December 30, 1999- January 13, 2000, No. 1/P/2000 has the following uniform name:
",2000-01-13; 1-p-2000").

As specified in Section 3.6, all the dates can have, in addition to the ISO format, also the date typical of the jurisdiction.

6.3.3. Unnumbered Measures

Measures not officially numbered in the publications may have a non-unequivocal identifier, because several measures of the same type can exist, issued on the same day by the same authority. To ensure that the uniform name is unambiguous, the numbers field MUST, in any case, contain a discriminating element, which can be any identifier used internally, and not published, by the authority (e.g., protocol).

If the authority does not have its own identifier, one identifier MUST be created for the name system. In order to easily differentiate it, such number is preceded by the string "lex-":

   number-lex = "lex-" 1*DIGIT

(e.g., "ministry.finances:decree:1999-12-20;lex-3")

It is responsibility of the authority issuing a document to assign a discriminating specification to it; in case of multiple authorities, only one of them is responsible for the assignment of the number to the document (e.g., the proponent).

The unnumbered measures published on an official publication (e.g., the Official Gazette), instead of by a progressive number are recognized by the univocal identifying label printed on the paper. Such an identifier, even if unofficial but assigned to a document in an official publication, is to be preferred because it has the clear advantage to be public and therefore easier to be found.

6.3.4. Multiple Numbers

Some legal documents (e.g., bills), even if unique, are identified by a set of numbers (e.g., the unification of cases or bills). In this case, in the numbers field, all the identifiers are reported, according to the following structure:

  numbers = document-id *("," document-id)

(e.g., "2000-06-12;c-10-97,c-11-97,c-12-97")

The characters which are not allowed (e.g., "/") or reserved (e.g., ":"), including the comma, cannot exist inside the document-id, and therefore MUST be turned into "-".

Where special characters contained in the number of the act are distinctive of the act itself (e.g. bill n. 123-bis (removal of 123) and n. 123/bis (return of 123)) and would disappear with the conversion to "-", a further ending must be added, allowing to distinguish the acts (e.g. bill n.123-bis-removal and 123-bis- return).

6.4. The annex Element

6.4.1. Formal Annexes

Although annexes are an integral part of the legal document, they may be referred to and undergo amendments separately from the act to which they are annexed. It is, therefore, necessary that both the main document as well as each formal individual annex is unequivocally identified.

Formal annexes may be registered as separate parts or together with a legal provision; they may also be autonomous in nature or not. In any case, they MUST be given a uniform name, which includes the uniform name of the source of law to which they are attached, and a suffix which identifies the annex itself.

The suffix of formal annexes includes the official heading of the annex and, possibly, further specifications (e.g., the title) which will facilitate the retrieval of the annex in case the identifier is missing:

    annex = annex-id *(";" specification)

(e.g., "region.sicily;council:deliberation:1998-02-12;14:annex.a; borders.park")

The characters which are not allowed (e.g. "/") or which are reserved (e.g. ":") must not be featured in the annex-id and therefore MUST be turned into ".".

6.4.2. Annexes of Annexes

When there are annexes to an annex, their corresponding identifiers are created by adding to the identifier of the original annex those of the annexes that are connected with it (that is, attached to it).

(e.g., Table 1 attached to the Annex A of the preceding legal act has the following uniform name:
"region.sicily;council:deliberation:1998-02-12;14:annex.a; borders.park:table.1;municipality.territories").

7. Specific Syntax of the Version Element of the "Expression"

7.1. The version Element

7.1.1. Different Versions of a Legislative Document

The creation of an updated text of a document may have one of the following forms:

  • "multi-version": when specific mark-ups which identify the modified parts of a document (added, substituted or deleted parts) and their related periods of effectiveness are indicated inside one single object (e.g., an xml file). Such a document will be able, in a dynamic way, to appear in different forms according to the requested date of effectiveness. In this document type, usually a set of metadata contains the lifecycle of the document (from the original to the last modification), including the validity time interval of each version and of each related text portion;

  • "single-version": when, on the contrary, a new and distinct object is created for each amendment to the text at a given time. Each object is, therefore, characterized by its own period of validity. In any case all the versions SHOULD be linked one another and immediately navigable.

In a "multi-version" document each time interval should have a link to the related in-force document version which can be therefore displayed. In a "single-version" document, the metadata should contain links to the all the previous modifications and a link only to the following version, if any.

[RFC8288] can be used as reference to establish links between different document versions, either in the "multi-version" or in the

"single-version" document. According to [RFC8288] the following relations are useful:

  • current (or last or last-version): in-force version

  • self: this version

  • next: next version

  • previous: previous version

  • first: original version

It is RECOMMENDED that these relations are inserted in the header of each version (if "single-version") or associated to each entry containing a single URN (if "multi-version").

7.1.2. Identification of the Version

In order to identify the different time versions of the same act, to the uniform name of the original document has to be added a specific suffix.

Such a suffix identifies each version of a legal provision and includes, first and foremost, one of the following elements:

  • the issuing date of the last amending measure taken into account;

  • the date in which the communication of the rectification or of the errata corrige, is published;

  • a specification which must identify the reason concerning the amendment (e.g., the specific phase of the legislative process), for the cases in which the date is not usually used (e.g., bills).

It is possible to add further specifications that will distinguish each of the different versions of the text to guarantee identifier unequivocalness. For example with regard to changes of the in-force or effectiveness of any partition or portion of the text itself (e.g., when the amendments introduced by an act are applied at different times) or different events occurring on the same date.

   version = (amendment-date / specification)
             *(";" (event-date / event))


  • amendment-date contains the issuing date of the last considered amendment or of the last communication of amendment. In case the original text introduces differentiated periods in which an act is effective and the information system produces one version for each of them, such element contains the string "original" expressed in the language of the act or version;

  • specification any information useful to identify unambiguously and univocally the version;

  • event-date contains the date in which a version is put into force, is effective or is published;

  • event is a name assigned to the event producing a further version (e.g., amendment, decision, etc.).

The issuing date of an amending act was chosen as identifier of a version because it can be obtained from the heading (formal data).

(e.g., the name "state:royal.decree:1941-01-30;12@1998-02-19" identifies the updated text of the "Royal Decree of 30/1/1941, No. 12" with the amendments introduced by the "Law Decree of 19/2/1998, No. 51", without any indication of its actual entry into force.
The same uniform name with the additional ending ";1999-01-01" indicates the in-force or effective version starting in a different date (from 1/1/99).

For a full compatibility, every updating of a text or of the effectiveness of a "multi-version" document implies the creation of a new uniform name, even if the object remains only one, containing the identifier of the virtually generated version, exactly as in the case of a "single-version" document. A specific meta-data will associate every uniform name with the period of time during which such a name together with its corresponding text is to be considered valid.

(e.g., the multi-version document containing the "R.D. of 01/30/1941, no. 12", updated by the amendments introduced by the "D.Lgs. of 02/19/1998, no. 51", contains the name of the original "state:royal.decree:1941-01-30;12" as well as the name of the updated version "state:royal.decree:1941-01-30;12@1998-02-19").

Please note that in case of attachments or annexes, the creation of a new version (even in the case of only one component) would imply the creation of a new uniform name for all the connected objects in order to guarantee their alignment (i.e., the main document, the attachments and annexes).

As specified in Section 3.6, all the dates can have, in addition to the ISO format, also the date typical of the jurisdiction.

8. Summary of the Syntax of the Uniform Names of the "lex" Namespace

; Structure of a Uniform Resource Name (URN) of the "lex" namespace
; - NID-lex = namespace
; - NSS-lex = specific name

URN-lex = "urn:" NID-lex ":" NSS-lex

NID-lex = "lex"

; Structure of a "lex" specific name

NSS-lex = jurisdiction ":" local-name

; Structure of the jurisdiction element

jurisdiction = jurisdiction-code *(";" jurisdiction-unit)

jurisdiction-code = 2*alf-dot

jurisdiction-unit = alf-dot

; Structure of the local-name element

local-name = work ["@" expression] ["$" manifestation]

; Structure of the work element

work = authority ":" measure ":" details *(":" annex)

; Structure of the authority element

authority = issuer *("+" issuer)

issuer = (institution *(";" body-function)) / office

institution = alf-dot

body-function = alf-dot

office = alf-dot

; Structure of the measure element

measure = measure-type *(";" specification)

measure-type = alf-dot

specification = alf-dot

; Structure of the details element

details = (dates / period) ";" numbers

dates = date *("," date)

period = alf-dot

numbers = (document-id *("," document-id)) / number-lex

document-id = alf-dot-oth

number-lex = "lex-" 1*DIGIT

; Structure of the annex element

annex = annex-id *(";" specification)

annex-id = alf-dot

; Structure of the expression element

expression = version [":" language]

; Structure of the version element

version = (amendment-date / specification)
       *(";" (event-date / event))

amendment-date = date

event-date = date

event = alf-dot

; Structure of the language element

language = 2*3alfa *["-" extlang] / 4*8alfa

extlang  = 3alfa *2("-" 3alfa)

; Structure of the manifestation element

manifestation = format ":" editor
             [":" component [":" feature]]

format = mime *(";" specification)

mime = alf-dot-hyp

editor = publisher *(";" specification)

publisher = alf-dot-hyp

component = part *(";" specification)

part = alf-dot-hyp

feature = attribute *(";" specification)

attribute = alf-dot-hyp

; Structure of the date

date = date-iso ["|" date-loc]

date-iso = year "-" month "-" day

year  = 4DIGIT
month = 2DIGIT
day   = 2DIGIT

date-loc = *(alfadot / other)

; Allowed, reserved and future characters
; - allowed = alfadot / other / reserved
; - reserved = ":" / "@" / "$" / "+" / "|" / ";" / "," / "~"
; - future = "*" / "!"

alf-dot = alfanum *alfadot
alf-dot-hyp = alfanum *(alfadot / "-")

alf-dot-oth = alfanum *(alfadot / other)

alfadot = alfanum / "."

alfa = lowercase / uppercase

alfanum = alfa / DIGIT / encoded

lowercase = %x61-7A        ; lower-case ASCII letters (a-z)

uppercase = %x41-5A        ; upper-case ASCII letters (A-Z)

DIGIT     = %x30-39        ; decimal digits (0-9)

encoded   = "%" 2HEXDIG

HEXDIG = DIGIT / %x41-46 / %x61-66 ; hex digits (0-9,A-F,a-f)

other    = "-" / "_" / "'" / "=" / "(" / ")"

9. The Procedure of Uniform Names Assignment

9.1. Specifying the jurisdiction Element of the LEX Identifier

Under the "lex" namespace, each country or international organization is assigned with a jurisdiction code, which characterizes the URNs of the source of law of that country or jurisdiction. This code is assigned according to ccTLD (as well as TLDN (Top Level Domain Name) or DN (Domain Name) for the organizations) representation and it is the value of the jurisdiction-code element, which preserves cross- country uniqueness of the identifiers.

9.2. Jurisdictional Registrar for Names Assignment

Any country or jurisdiction, who intends to adopt this schema, MUST identify a Jurisdictional Registrar, an organization which shares and defines the structure of the optional part (jurisdiction-unit) of the name, according to the organization of the state or institution (for details see Section 2.2). It must appoint a Jurisdictional Registrar and inform the Designed Experts, together with the registration of a jurisdiction code. For example, in a federal state a jurisdiction-unit corresponding to the name of each member state
(e.g. "br;sao.paulo", "br;minas.gerais", etc.) may be defined.

The process of assigning the local-name is managed by each specific country or jurisdiction under the related jurisdiction element.

In any country the Jurisdictional Registrar shares and defines the assignment of the primary elements (issuing authority and type of legal measure) of the local names considering the characteristics of its own state or institution organization.

Such a Registrar MUST establish, according to the guidelines indicated in this document, a uniform procedure within the country or organization to define local-name elements, to take decisions upon normalizations and finally to solve and avoid possible name collisions as well as to maintain authoritative registries of various kinds (e.g., for authorities, types of measures, etc.). In particular, accurate point-in-time representations of the structure and naming of government entities are important to semantically-aware applications in this domain.

Moreover, the Registrar shares and defines the rules to construct partition IDs for each document type, possibly in accordance with those already defined in other jurisdictions.

Finally, the Registrar will develop and publish the rules and the guidelines for the local-name construction as well as the predefined values and codes. The Registrar should also promote the urn:lex identifier for the sources of law of its jurisdiction.

Such a set of rules will have to be followed by all institutional bodies adopting the URN LEX identification system in a country or jurisdiction, as well as by private publishers, and each of them will be responsible for assigning names to their domains.

9.3. Identifier Uniqueness

Identifiers in the "lex" namespace are defined through a jurisdiction element assigned to the sources of law of a specific country or organization, and a local-name assigned by the issuing authority, in conformance with the syntax defined in Section 5. The main elements (authority and type of measure) of the local-name are defined by the Jurisdictional Registrar, so that it is ensured that the constructed URNs are unique. The Jurisdictional Registrar MUST provide clear documentation of rules by which names are to be constructed, and MUST update and make accessible its registries.

Any enacting authority is responsible to define formal parameters to guarantee local name uniqueness by attributing, if necessary, a conventional internal number, which, combined with the other local- name components (authority, measure and date), builds a unique identifier. Uniqueness is achieved by checking against the catalogue of previously assigned names.

9.4. Identifier Persistence Considerations

The persistence of identifiers depends on the durability of the institutions that assign and administer them. The goal of the LEX schema is to maintain uniqueness and persistence of all resources identified by the assigned URNs.

In particular, the CNR, as proposer, is responsible of maintaining the uniqueness of the jurisdiction element; given that the jurisdiction is assigned on the basis of the long-held ccTLD representation of the country (or the TLDN or DN of the organization) and that the country or organization associated code is expected to continue indefinitely, the URN also persists indefinitely.

The rules for the construction of the name are conceived to delegate the responsibility of their uniqueness to a set of authorities which is identified within each country or organization.

Therefore, each authority is responsible for assigning URNs which have a very long life expectancy and can be expected to remain unique for the foreseeable future. Practical and political considerations, as well as diverse local forms of government organization, will result in different methods of assigning responsibility for different levels of the name.

Where this cannot be accomplished by the implementation of an authoritative hierarchy, it is highly desirable that it be done by creating consensus around a series of published rules for the creation and administration of names by institutions and bodies that operate by means of collaboration rather than compulsion.

Issuing authorities that operate in more localized scopes, ranging from the national down to the very local, MUST equally take responsibility for the persistence of identifiers within their scope.

10. Recommendations for the Resolution Process

10.1. The General Architecture of the System

The task of the resolution service is that of associating a LEX identifier with a specific document address on the network. By contrast with systems that can be constructed around rigorous and enforceable engineering premises, such as DNS, the "lex" namespace resolver will be expected to cope with a wide variety of inputs incomplete or partially incorrect, particularly those created by the automated extraction of references from texts. In this document, the result is a particular emphasis on a flexible and robust resolver design.

The system has a distributed architecture based on two fundamental components: a chain of information in DNS (Domain Name System) and a series of resolution services from URNs to URLs, each competent within a specific domain of the namespace.

The client retrieves the document associated with this URN using the procedure described in [RFC3404], which starts with a DNS NAPTR query.

A resolution service can delegate the resolution and management of hierarchically-dependent portions of the name. Delegation of this responsibility will not be unreasonably withheld provided that the processes for their resolution and management are robust and are followed.

For the "lex" namespace, CNR will maintain in the lex-nameserver (see Section 12) the root zone of the chain resolution (equivalent to "", see [RFC3405]) and, in correspondence with the adhesion (see Section 2.2) of a new country (e.g., "br") or organization, will update the DNS information with a new record to delegate the relative resolution. This may be obtained by a regular expression that matches the initial part of the URN (e.g., "urn:lex:br") and redirects towards the proper zone (e.g., "").

Likewise the institution responsible for the jurisdiction uniform names (e.g., "urn:lex:br") has the task of managing the relative root in the DNS system (e.g., "" zone) and routing the resolution towards its resolvers on the basis of parts of the uniform names. In similar way it can delegate the resolution of country/organization sub-levels (e.g., "urn:lex:br;sao.paolo") towards the relative zone (e.g., "").

Such DNS routing chain does not work for all the URN components containing %-encoded characters. Therefore, when converting a lex:URN in UTF-8 code to a DNS query, clients MUST perform any necessary punycode conversion [RFC5891] before sending the query.

The resolution service is made up of two elements: a knowledge base (consisting in a catalogue or a set of transformation rules) and a software to query the knowledge base itself.

10.2. Catalogues for Resolution

Incompleteness and inaccuracy are rather frequent in legal citations, and incomplete or inaccurate uniform names of the referred document are thus likely to be built from textual references (this is even more frequent if they are created automatically through a specific parser). For this reason, the implementation of a catalogue, based on a relational-database, is suggested, as it will lead to a higher flexibility in the resolution process.

In addition the catalogue must manage the aliases, the various versions and languages of the same source of law as well as the related manifestations.

It is suggested that each enacting authority implements its own catalogue, assigning a corresponding unambiguous uniform name to each resource.

10.3. Suggested Resolver Behaviour

First, the resolver SHOULD separate the part corresponding to the partition ID, through the "~" separator, from the document name.

The resolution process SHOULD implement a normalization of the uniform name to be resolved. This may involve transforming some components to the canonical form (e.g., filling out the acronyms, expanding the abbreviations, unifying the institution names, standardizing the type of measures, etc.). For this function authorities and types of measure registers are useful.

The resolver SHOULD then query the catalogue searching for the URN which corresponds exactly to the given one (normalized if necessary). Since the names coming from the references may be inaccurate or incomplete, an iterative, heuristic approach (based on partial matches) is indicated. Incomplete references (not including all the elements to create the canonical uniform name) are normal and natural; for a human reader, the reference would be "completed" by contextual understanding of the reference in the document in which it occurs.

In this phase, the resolver should use the partition ID information to retrieve, if it is possible, only the referred partition, otherwise to return the entire document.

Lacking more specific indications, the resolver SHOULD select the best (most recent) version of the requested source of law, and provide all the manifestations with their related items. A more specific indication in the uniform name to be resolved will, of course, result in a more selective retrieval, based on any suggested expression and/or manifestations components (e.g. date, language, format, etc.).

Finally, the resolver SHOULD append to URLs the "#" character followed by partition ID, transforming it in a URI fragment for browser pointing.

11. Security Considerations

Security considerations are those normally associated with the use and resolution URNs in general. Additional security considerations concerning the authenticity of a document do not pertain to the LEX specifications, but they pertain security and trust issues which can be addressed with other means, like digital signature, data encryption, etc.

12. IANA Considerations

IANA has already registered the "lex" namespace, according to the template at section 2. Registration has been accomplished as the Formal URN Namespace registry described by [RFC8141].

In addition, to activate a distributed resolution system, the one-off registration of the following NAPTR records is requested:

in the URN.ARPA domain:

     IN NAPTR  1    0  ""  ""  "!^urn:lex:!_lex!i"  .
_lex IN NAPTR  10  10  ""  ""  ""  lex-nameserver.

in the URN.URI.ARPA domain:

     IN NAPTR  1    0  ""  ""  "!^urn:lex:!_lex!i"  .
_lex IN NAPTR  10  10  ""  ""  ""  lex-nameserver.

where lex-nameserver indicates the server of the organization that is responsible for the resolution of the "lex" namespace and will be communicated by the applicant when the application is approved.

13. Acknowledgements

The authors of this document wish to thank all the supporters for giving suggestions and comments.

They are also grateful to the Legislative XML community [SART] for the interesting discussions on this topic and to the Working Group "Identification of the legal resources through URNs" of Italian NormeInRete project for the provided guidance [SPIN].

The authors owe a debt of gratitude to Tom Bruce, director of the Legal Information Institute of the Cornell University Law School, for his contribution in revising this document and sharing fruitful discussions which greatly improved the final draft. The authors wish to specially thank Marc van Opijnen (Dutch Ministry of Security and Justice) for his valuable comments on LEX specifications which contributed to improve the final result, as well as for the common work aimed to harmonize ECLI and LEX specifications. Thanks also to Joao Alberto de Oliveira Lima, legislative system analyst of the Brazilian Federal Senate, and to Attila Torcsvari, information management consultant, for their detailed comments on the first drafts of this document, which provided significant hints to the final version of the standard, and to Robert Richards of the Legal Information Institute (Cornell University Law School), promoter and maintainer of the Legal Informatics Research social network, as well as to the members of this network, for their valuable comments on this proposal.

Finally, many thanks go to Loriana Serrotti who significantly contributed to the first drafting of this document.

14. References

14.1. Normative References

Freed, N. and N. Borenstein, "Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies", RFC 2045, DOI 10.17487/RFC2045, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, , <>.
Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Four: The Uniform Resource Identifiers (URI)", RFC 3404, DOI 10.17487/RFC3404, , <>.
Mealling, M., "Dynamic Delegation Discovery System (DDDS) Part Five: URI.ARPA Assignment Procedures", BCP 65, RFC 3405, DOI 10.17487/RFC3405, , <>.
Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, , <>.
Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", STD 68, RFC 5234, DOI 10.17487/RFC5234, , <>.
Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, , <>.
Klensin, J., "Internationalized Domain Names in Applications (IDNA): Protocol", RFC 5891, DOI 10.17487/RFC5891, , <>.
Alvestrand, H., Ed. and C. Karp, "Right-to-Left Scripts for Internationalized Domain Names for Applications (IDNA)", RFC 5893, DOI 10.17487/RFC5893, , <>.
Klensin, J., "Internationalized Domain Names for Applications (IDNA): Background, Explanation, and Rationale", RFC 5894, DOI 10.17487/RFC5894, , <>.
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, , <>.
Saint-Andre, P. and J. Klensin, "Uniform Resource Names (URNs)", RFC 8141, DOI 10.17487/RFC8141, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.
Nottingham, M., "Web Linking", RFC 8288, DOI 10.17487/RFC8288, , <>.
International Organization for Standardization, "Data elements and interchange formats - Information interchange - Representation of dates and times", ISO Standard 8601, .
"HTML", W3C REC html, W3C html, <>.

14.2. Informative References

Francesconi, E., "Technologies for European Integration. Standards-based Interoperability of Legal Information Systems", ISBN 978-88-8398-050-3, .
"Functional Requirements for Bibliographic Records", n.d., <>.
The European Commission, "The Hague Conference on Private International Law "Access to Foreign Law in Civil and Commercial Matters. Conclusions and Recommendations"", , <>.
The Standing Committee of the IFLA Cataloguing Section Berlin/Munich\: De Gruyter Saur, "International Standard Bibliographic Description - Consolidated Edition.", ISBN 978-3-11-026379-4, .
International Organization for Standardization, "Codes for the representation of names of countries and their subdivisions -- Part 1: Country codes".
Peruginelli, G., Ed. and M. Ragona, Ed., "Law via the Internet. Free Access, Quality of Information, Effectiveness of Rights", ISBN 9788883980589, .
Sartor, G., Palmirani, M., Francesconi, E., and M. Biasiotti, "Legislative XML for the Semantic Web. Principles, Models, Standards for Document Management, Law, Governance and Technology Series", ISBN 978-94-007-1887-6, .
Spinosa, P., "The Assignment of Uniform Names to Italian Legal Documents, URN-NIR 1.4", ITTIG technical Report n. 8/2010., .
"RDF Schema 1.1", W3C REC rdf-schema, W3C rdf-schema, <>.

Authors' Addresses

PierLuigi Spinosa
Via Zanardelli, 15
50136 Firenze
Enrico Franceseconi
Consiglio Nazionale delle Ricerche (CNR)
Via de' Barucci, 20
50127 Firenze
Phone: +39 055 43995
Caterina Lupo
Via San Fabiano, 25
117 Roma