Internet-Draft CBOR-IP June 2021
Bormann Expires 4 December 2021 [Page]
CBOR Working Group
Intended Status:
Standards Track
C. Bormann
Universität Bremen TZI

CBOR Tags for CoAP Content Formats


This document describes a set of CBOR Tags that encode CoAP Content-Formats (RFC 7252).

Status of This Memo

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This Internet-Draft will expire on 4 December 2021.

Table of Contents

1. Introduction

[RFC8949] defines a number of CBOR Tags for common items.

Often, there is a need to identify a media type (or content type, i.e., media type optionally used with parameters) for a byte string in a CBOR data item.

[RFC7252] defines the concept of a Content-Format, which is a short 16-bit unsigned integer that identifies a specific content type, optionally together with a content encoding.

This short specification allocates tag numbers 1668546560 (0x63740000) to 1668612095 (0x6374FFFF) for the tagging of representations of specific content formats. The tag content tagged with tag number NNNN (in above range) is a byte string that is to be interpreted as a representation of the content format NNNN-1668546560.

2. Examples

[IANA.core-parameters] defines content formats that can be used as examples:

3. IANA Considerations

IANA is requested to allocate the tag numbers 1668546560 (0x63740000) to 1668612095 (0x6374FFFF) as follows:

Data Item: byte string
Semantics: representation of content-format (RFC7252) NNNN-1668546560

4. Normative References

IANA, "Constrained RESTful Environments (CoRE) Parameters", <>.
Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, , <>.
Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", STD 94, RFC 8949, DOI 10.17487/RFC8949, , <>.


Michael Richardson prompted us to finally write this up.

Author's Address

Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen