- From: Bert Bos <bert@w3.org>
- Date: Sat, 07 Oct 2006 17:11:09 -0700
- To: www-style@w3.org
Bjoern Hoehrmann wrote: > Hi, > > Simon Pieters uncovered a problem with namespace prefix handling in > the Selectors Working Draft when reviewing the XBL2 Working Draft. It > is currently left to higher level specifications how to look up the > namespace name that corresponds to a prefix in a selector. This lack > of a definition results in errors in specifications that use selectors, > for example, [...] > As this is highly undesirable, the Selectors specification should both > explain this problem and address the common cases directly. A possible > solution would be as follows: specifications must define a lookup mech- > anism. If the mechanism is an algorithm, the Selector implementation > must pass the prefix (transformed to lower-case) to the algorithm. If > the mechanism is a hash with case-insensitive keys, the key that equals > the prefix identifies the namespace name. If the mechanism is a hash > with case-sensitive keys, the keys are put in some order and the first > key that matches the prefix case-insensitively identifies the namespace > name (the order would have to be defined). Specifications may define > other lookup mechanisms. If no mechanism is defined, or the mechanism > fails to identify a namespace name, the given prefix is considered not > declared for the purposes of the specification. I think it's a good idea for the Selectors spec to say explicitly that the namespace prefixes are case-insensitive, but it has no business saying anything about canonicalization, APIs or the scope of prefix declarations. Inside CSS, the scope is defined by the Namespace module, while canonicalization and APIs are not needed by CSS and thus not defined. Some other technology that uses Selectors can define these aspects any way it likes: case-preserving or not, normalizing or not, lexical or dynamic scope. It would be good if two similar APIs made similar choices, but the Selectors spec doesn't need to say what those choices should be. Bert -- Bert Bos ( W 3 C ) http://www.w3.org/ http://www.w3.org/people/bos W3C/ERCIM bert@w3.org 2004 Rt des Lucioles / BP 93 +33 (0)4 92 38 76 92 06902 Sophia Antipolis Cedex, France
Received on Thursday, 19 October 2006 13:06:12 UTC