Note: This RFC has been obsoleted by RFC 8259Source of RFC: json (app)
Errata ID: 4298
Reported By: Michael Kay
Date Reported: 2015-03-11
Rejected by: Barry Leiba
Date Rejected: 2015-03-11
Section 7 Strings says:
It should say:
Something along the lines 4hexdig hexdig = 0..9 A..F a..f
The prose states that within a six-character escape sequence starting \u, the hex digits can be either upper or lower case. But the grammar only allows upper case, because it uses the symbol HEXDIG which is defined in RFC 5234 to include upper case A..F only. There is thus an inconsistency beween the grammar and the prose, and although most readers are likely to know which to believe, the spec is formally ambiguous on this point.
The reporter doesn't understand RFC 5234. Look in Section 2.3 (Terminal Values), and see this:
> ABNF strings are case insensitive and the character set for these
> strings is US-ASCII.
There is no inconsistency, and the text as written allows both upper and lower case for the hex digits.