- From: Pete Cordell <petejson@codalogic.com>
- Date: Mon, 18 Nov 2013 10:05:07 -0000
- To: "Martin J. Dürst" <duerst@it.aoyama.ac.jp>, "Henry S. Thompson" <ht@inf.ed.ac.uk>
- Cc: "John Cowan" <cowan@mercury.ccil.org>, "IETF Discussion" <ietf@ietf.org>, "JSON WG" <json@ietf.org>, "Anne van Kesteren" <annevk@annevk.nl>, <www-tag@w3.org>, "es-discuss" <es-discuss@mozilla.org>
Given the history below, would it be sensible to accept BOMs for UTF-8 encoding, but not for UTF-16 and UTF-32? In other words, are BOMs needed and/or used in the wild for UTF-16 and UTF-32? Maybe the text can say something like "SHOULD accept BOMs for UTF-8, and MAY accept BOMs for UTF-16 and / or UTF-32"? Thanks, Pete Cordell Codalogic Ltd C++ tools for C++ programmers, http://codalogic.com Read & write XML in C++, http://www.xml2cpp.com ----- Original Message ----- From: ""Martin J. Dürst"" <duerst@it.aoyama.ac.jp> To: "Henry S. Thompson" <ht@inf.ed.ac.uk> Cc: "John Cowan" <cowan@mercury.ccil.org>; "IETF Discussion" <ietf@ietf.org>; "Paul Hoffman" <paul.hoffman@vpnc.org>; "JSON WG" <json@ietf.org>; "Joe Hildebrand (jhildebr)" <jhildebr@cisco.com>; "Anne van Kesteren" <annevk@annevk.nl>; <www-tag@w3.org>; "es-discuss" <es-discuss@mozilla.org> Sent: Thursday, November 14, 2013 11:14 AM Subject: Re: [Json] JSON: remove gap between Ecma-404 and IETF draft > Hello Henry, others, > > On 2013/11/14 18:44, Henry S. Thompson wrote: >> John Cowan writes: >> >>> Joe Hildebrand (jhildebr) scripsit: >>> >>>> If 404 doesn't allow [a BOM], I don't see a strong need to add it. >>>> Parsers can always be more forgiving of what they will parse than what >>>> the spec says, particularly since section 9 says "A JSON parser MAY >>>> accept non-JSON forms or extensions". >>> >>> It's not clear that 404 disallows it, since 404 is defined in terms of >>> characters, and a BOM is not a character but an out-of-band signal. >> >> I think this is a crucial observation. > > Yes, and I think it's based on the experience with XML. But while this > experience may be applicable to JSON, Anne's original comment about the > BOM and XMLHttpRequest suggests that 404 actually currently does not > tolerate a BOM, and that implementations (except for XMLHttpRequest) also > don't. > > To give some historic background, the BOM for UTF-8 wasn't in the first > edition of XML (http://www.w3.org/TR/1998/REC-xml-19980210#sec-guessing). > It only later came in because Microsoft used it for notepad to be able to > quickly distinguish between UTF-8 and the legacy system encoding. Because > many people were writing some XML by hand, and some of them were using > notepad, the pressure on XML to accept a BOM at the start of an UTF-8 file > mounted, and it was included in the second edition of the XML > Recommendation (http://www.w3.org/TR/2000/REC-xml-20001006#sec-guessing). > > Compared to XML, JSON may be much less edited by hand, or much less edited > on notepad, or otherwise just have a different history from XML, but we > have to make sure. > > Regards, Martin. > > >> I note that XML approaches >> this problem in what might be a useful way. The XML ABNF makes no >> mention of BOM, it's not part of any XML document as such. But it >> _is_ allowed. The relevant wording [1] is: >> >> Entities ... may begin with the Byte Order Mark described by Annex H >> of [ISO/IEC 10646:2000], section 16.8 of [Unicode] (the ZERO WIDTH >> NO-BREAK SPACE character, #xFEFF). _This is an encoding signature,_ >> _not part of either the markup or the character data of the XML_ >> _document._ XML processors must be able to use this character to >> differentiate between UTF-8 and UTF-16 encoded documents. [emphasis >> added] >> >> ht >> >> [1] http://www.w3.org/TR/REC-xml/#charencoding > _______________________________________________ > json mailing list > json@ietf.org > https://www.ietf.org/mailman/listinfo/json
Received on Monday, 18 November 2013 10:06:10 UTC