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Chris Nokleberg <chris@s...> wrote: > The Namespace spec adds additional conformance constraints beyond XML 1.0: > * All element types and attribute names contain either zero or one colon. > * No entity names, PI targets, or notation names contain any colons. > > Is a non-validating SAX2 parser required to check these constraints? > My suggestion is that it should be required to check iff the > http://xml.org/sax/features/namespaces feature is true. > Firstly, I think after reading the namespaces rec [1] section 6 carefully, that the two "constraints" you quote above are not, in fact, namespace constraints, rather they are just a clarification of the effects of using the Qname and NCName productions in the places that the recommendation dictates. Therefore, it follows that when namespaces are enabled, any XML processor (whether SAX or not, validating or not) should report a fatal error when the QName or NCName productions are not matched. This is because syntax errors are well-formedness errors and reporting well-formedness errors as fatal errors is in keeping with XML 1.0 [2]. The rec [1] does, however, dictate a number of additional namespace constraints. It does not dictate the effect that these constraints should have on processing but it is my belief that nearly are all fatal errors. Let me explain why. There is only a short list of namespace constraints (NSC):- - Namespace Constraint: Leading "XML" The "XML" prefix is reserved for use by XML-related specifications. It is unwise for XML processors to actually check for this because they would risk becoming broken when new specifications are created. I think this is a directive at document creators, not processor implementers. - Namespace Constraint: Prefix Declared A namespace prefix must be declared before it is used. This should be a fatal error because the XML processor will be unable to report to the application the correct namespace uri for the name. This should not be allowed to happen, as it could have unpredictable results for the application. - 5.3 Uniqueness of attributes When a single namespace uri is bound to two different prefixes it is possible for duplicate attributes to be created, even though they appear to be different under XML 1.0 rules. Duplicate attributes are disallowed in XML 1.0 [2] as a well-formedness constraint. Therefore they should be reported as fatal errors. [1] http://www.w3.org/TR/REC-xml-names/ [2] http://www.w3.org/TR/REC-xml Regards Rob Lugt ElCel Technology http://www.elcel.com/
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