RFC 4647, "Matching of Language Tags", September 2006

Errata ID: 8287
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Randall Edward Cotton
Date Reported: 2025-02-08

Section 3.1 says:

   3.  Lookup (Section 3.4) matches a language priority list consisting
       of basic language ranges to sets of language tags to find the one
       exact language tag that best matches the range.

It should say:

   3.  Lookup (Section 3.4) matches a language priority list consisting
       of basic and/or extended language ranges to sets of language tags
       to find the one exact language tag that best matches the range.

Notes:

The original text illustrated above states that the 'lookup' matching scheme operates using 'basic language ranges' as opposed to 'extended language ranges'. However, the description of the 'lookup' matching scheme in section 3.4, in its last two paragraphs (beginning with "In some cases,"), describes how extended language ranges are processed by the 'lookup' matching scheme. Thus, section 3.1 indicates that 'extended language ranges' are not supported by the 'lookup' matching scheme, while section 3.4 indicates the opposite and describes how they are to be supported.

This contradiction can lead to confusion for the reader and compliance ambiguity for the implementor.

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