Re: [Ltru] Re: Case-insensitive rules (Was: I-D ACTION:draft-ietf-ltru-4646bis-01.txt)

[John Cowan <cowan at ccil.org>]

Doug Ewell scripsit:

> Can you find an RFC that states unequivocally that ABNF strings are 
> case-insensitive?  That would allow us to defend simplifying the 
> productions.

No problem.  RFC 2234, which defines ABNF for IETF purposes, says
in Section 2.3:

   ABNF permits specifying literal text string directly, enclosed in
   quotation-marks.  Hence:

        command     =  "command string"

   Literal text strings are interpreted as a concatenated set of
   printable characters.

        NOTE:     ABNF strings are case-insensitive and
                  the character set for these strings is us-ascii.

   Hence:

        rulename = "abc"

   and:

        rulename = "aBc"

   will match "abc", "Abc", "aBc", "abC", "ABc", "aBC", "AbC" and "ABC".

                To specify a rule which IS case SENSITIVE,
                   specify the characters individually.

   For example:

        rulename    =  %d97 %d98 %d99

   or

        rulename    =  %d97.98.99

   will match only the string which comprises only lowercased
   characters, abc.

-- 
John Cowan                                <cowan at ccil.org>
Yakka foob mog.  Grug pubbawup zink wattoom gazork.  Chumble spuzz.
    -- Calvin, giving Newton's First Law "in his own words"

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