[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: Dumb questions about PUBLIC IDs
At 10:34 2001 05 05 -0400, Charles Reitzel wrote: >I'm curious. I don't see it in the XML spec, but are PUBLIC IDs really supposed to be in the form "-//Foo//Bar//Baz". No, what you see in the XML spec is what public ids are. Other than a restriction on the character set, they have pretty much any form you want. (Note, though, that there is a normalization process for public ids that compresses consecutive whitespace, etc.) SGML declares a special kind of public identifier known as a Formal public identifier (FPI) that has a certain structure that includes //'s for field separators (though what you show above isn't a valid FPI because it doesn't satisfy all the syntax constraints for an FPI). > Is this an ISO format? FPIs are an ISO format. >If so, where is it defined? They are described both in the SGML standard ISO 8879 and further defined/discussed in ISO 9070. >The grammatical production "PubidLiteral" and its rules for space compression seem to encompass either a URI, the format above, and just about anything else you'd like to put in there. Other than the character restrictions, a public id has no syntax restrictions. As far as encompassing URIs, not all characters that are allowed (unescaped) in URIs are allowed in public ids and vice versa, so other than both being strings, there really isn't a strong syntactic relationship. >Tool survey: IE5.5 won't display a file unless the PUBLIC ID is in the format above. XML Spy doesn't care. Expat doesn't care. Xerces doesn't care. There is an OASIS Technical Committee working on defining an XML Catalog to map public ids to URIs: http://www.oasis-open.org/committees/entity/ Some of us hope that support for XML Catalog will someday be included in all important XML processing tools. paul
|
PURCHASE STYLUS STUDIO ONLINE TODAY!Purchasing Stylus Studio from our online shop is Easy, Secure and Value Priced! Download The World's Best XML IDE!Accelerate XML development with our award-winning XML IDE - Download a free trial today! Subscribe in XML format
|