[Ltru] Language Ranges

[Mark Davis <mark.davis at icu-project.org>]

The main issue I have with the document as it stands is that it neglects a very important case. The general case of language matching involves having a *list* of language ranges. You take a list like "en-US en fr it" and use it for either matching or lookup. So I would suggest adding the following text. (It probably needs fleshing out a bit, but this is a start.).


2.3 Language Range Lists

A language range list is a space-delimited list of zero or more language ranges. An extended language range list contains extended language ranges; a basic language range list is limited to containing basic language ranges. In matching, anything that matches any element of the list according to the above options is included. (With distance metrics, the shortest distance from any element in the list is the one used for the overall distance).

In lookup, the list is examined from first to last for a match, according to the above options. For example, starting with the list range "zh-Hant-CN en-US fr", and using Lookup with truncation as in 2.1.1, the lookup would progressively search for content as shown below:

List Range to match: zh-Hant-CN en-US fr
1. zh-Hant-CN
2. zh-Hant
3. zh
4. en-US
5. en
6. fr
7. (default content or the empty tag)

2.3 Meaning of Language Tags and Ranges [RENUMBER to 2.4...]

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