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Reported by Tab Atkins Jr. and fantasai In 4.1 and G.2, the NUMBER, PERCENTAGE, and DIMENSION tokens (amongst others in G.2 such as LENGTH and ANGLE) depend on the {num} macro which is defined as # num [0-9]+|[0-9]*\.[0-9]+ in 4.2, and as # num [0-9]+|[0-9]*"."[0-9]+ in G.2. The optional leading + or - sign that can be used with these tokens is tokenized as a separated DELIM token, and is combined with the following token during parsing. This implies that you can insert a comment between the sign and the number. This is undesirable for the following reasons: 1. It's unintuitive and doesn't serve much useful purpose; 2. It's not interoperable, since Gecko and PrinceXML both parse the sign as 3. part of the NUMBER/etc token, whilst other UAs seem to follow the spec; 3. It makes it difficult for spec authors to talk about numbers and such in grammar terms, because they must always remember to also allow an optional + or - DELIM preceding the tokens. Conversation begins: Bug report: http://lists.w3.org/Archives/Public/www-style/2012Apr/0639.html
The WG resolved to include the sign in the NUMBER, PERCENTAGE, and DIMENSION tokens: http://lists.w3.org/Archives/Public/www-style/2012May/0235.html
The wording proposed and added to the errata doc at http://www.w3.org/Style/css2-updates/REC-CSS2-20110607-errata.html is to clarify that neither comments nor spaces are allowed after the sign in property values that are defined as <number>, <length> or <percentage>: In 4.3.1 (Integers and real numbers), insert the word "immediately" as follows: | Both integers and real numbers may immediately be preceded by a "-" | or "+" to indicate the sign. Proposal: http://lists.w3.org/Archives/Public/www-style/2012May/0727.html
The proposal and errata item in Comment 2 does not match the resolution made by the WG (see Comment 1). Objection to proposed change: http://lists.w3.org/Archives/Public/www-style/2012May/0741.html
Bjoern Hoehrman notes that 4.1.1 (Tokenization) says: # COMMENT tokens do not occur in the grammar (to keep it readable), # but any number of these tokens may appear anywhere outside other # tokens. and so the proposal to add the word "immediately" is not sufficient to solve the problem in any case; although Kang-Hao (Kenny) Lu notes that 4.1 says: # In this specification, the expressions "immediately before" or # "immediately after" mean with no intervening white space or # comments. It seems that editorial work is needed to remove the conflict between these two sentences if the proposal to solve the issue by inserting the word "immediately" is adopted. Conversation begins: http://lists.w3.org/Archives/Public/www-style/2012May/0727.html
Tab Atkins Jr. notes that to implement the resolution, it is instead necessary to change the {num} macro, and Kang-Hao (Kenny) Lu notes that it is also necessary to change the 'term' production in G.1. Conversation begins: http://lists.w3.org/Archives/Public/www-style/2012May/0727.html
Proposal [http://lists.w3.org/Archives/Public/www-style/2012Jun/0410.html]: 1. In 4.1.1, change the "num" macro to: | num ['+'|'-']?([0-9]+|[0-9]*\.[0-9]+) 2. In G.2, change the "num" macro to: | num ['+'|'-']?([0-9]+|[0-9]*"."[0-9]+) 3. In G.2, remove the "unary_operator" production entirely. 4. In G.2, change the "term" production to: | term | : NUMBER S* | PERCENTAGE S* | LENGTH S* | EMS S* | EXS S* | | ANGLE S* | TIME S* | FREQ S* | | STRING S* | IDENT S* | URI S* | hexcolor | function | ;
Correction: steps 3 and 4 in the proposal in Comment 6 apply to G.1, not G.2.
(In reply to comment #0) > 2. It's not interoperable, since Gecko and PrinceXML both parse the sign as 3. > part of the NUMBER/etc token, whilst other UAs seem to follow the spec; To make this data complete, I'd note that IE9 is also Gecko-like from my testing. [1] (In reply to comment #6) > Proposal [http://lists.w3.org/Archives/Public/www-style/2012Jun/0410.html]: I'd hope that this is fixed along with bug 17510 . They were in the same thread. [1] http://lists.w3.org/Archives/Public/www-style/2012Apr/0082