IEEE Standards Interpretations for IEEE Std 1003.2™-1992 IEEE Standard for Information Technology--Portable Operating System Interfaces (POSIX®)--Part 2: Shell and Utilities
Copyright © 1996 by the Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue New York, New York 10016-5997 USA All Rights Reserved.
Interpretations are issued to explain and clarify the intent of a standard and do not constitute an alteration to the original standard. In addition, interpretations are not intended to supply consulting information. Permission is hereby granted to download and print one copy of this document. Individuals seeking permission to reproduce and/or distribute this document in its entirety or portions of this document must contact the IEEE Standards Department for the appropriate license. Use of the information contained in this document is at your own risk.
IEEE Standards Department, Copyrights and Permissions, 445 Hoes Lane, Piscataway, New Jersey 08855-1331, USA
Interpretation Request #27
Topic: LC_COLLATE Relevant Clauses: 22.214.171.124 Classification: Ambiguous situation
(Subclause 126.96.36.199, LC_COLLATE, lines 1654-1658 in Draft 12)
"User- defined ordering of collating elements. Each collating element shall be assigned a collation value defining its order in the character (or basic) collation sequence. This ordering is used by regular expressions and pattern matching and, unless collation weights are explicitly specified, also as the collation weight to be used in sorting."
Given this passage, assume there are two similar LC_COLLATE fragments. The fragments include lowercase letters only to simplify the examples.
Here is the first fragment: <a <a>;<a>;<a> <a-grave<a>;<a-grave>;<a-grave> <a-acute<a>;<a-acute>;<a-acute> <b <b>;<b>;<b> <c <c>;<c>;<c> <d <d>;<d>;<d> . . . <z <z>;<z>;<z> . . .
Here is the second fragment: <a <a>;<a>;<a> <b <b>;<b>;<b> <c <c>;<c>;<c> <d <d>;<d>;<d> . . . <z <z>;<z>;<z> <a-grave<a>;<a-grave>;<a-grave> <a-acute<a>;<a-acute>;<a-acute> . . .
Suppose a user wanted to find all words that begin with a letter in the range a-c. At the XoJIG meeting, we agreed that a locale built using the first fragment returns words that begin with <a>, <a-grave>, <a-acute>, <b>, and <c>. However, there were varying opinions about whether the second fragment would return the same results, or would exclude <a-grave> and <a-acute>.
So the question is this: Should an RE run against a locale built using the second fragment include the accented a)s in the range because they are defined as being in the same equivalence class as <a>, or should it exclude the accented a's because they are listed outside the range of a-c?
The standard is ambiguous in this area, since it is not clear what the phrase "collation sequence order" means or is. The two possibilities are "the order in locale file", or "the order determined by the weights in the locale file". The standard allows either behavior. Concern over the wording of this area has been forwarded to the Sponsors of the standard.
Rationale for Interpretation