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Bug 1515 - Contradictory statement: casting to xs:notation permitted/allowed
Summary: Contradictory statement: casting to xs:notation permitted/allowed
Alias: None
Product: XPath / XQuery / XSLT
Classification: Unclassified
Component: Functions and Operators 1.0 (show other bugs)
Version: Last Call drafts
Hardware: Other Linux
: P2 normal
Target Milestone: ---
Assignee: Ashok Malhotra
QA Contact: Mailing list for public feedback on specs from XSL and XML Query WGs
Depends on:
Reported: 2005-06-29 19:35 UTC by Frans Englich
Modified: 2005-09-29 11:30 UTC (History)
0 users

See Also:


Description Frans Englich 2005-06-29 19:35:19 UTC
When reading section "17.1 Casting from primitive types to primitive types"    
found in the working draft of 4th April,[1] I think contradictory statements    
can be found. The first statement, which is the second paragraph in the    
section, reads:    
"[XML Schema Part 2: Datatypes Second Edition] defines xs:NOTATION as an    
abstract type. Thus, casting to xs:NOTATION is not permitted."    
However, when I interpret the "casting table" found a bit below, I judge that    
xs:NOTATION can be cast to itself(and maybe xs:string).     
What is correct becomes quickly complicated, in my opinion. I don't see how the    
situation of casting from xs:NOTATION to xs:NOTATION would occur in practice,    
since the data type is abstract. Hence, does the table document a casting which    
is in theory doable but cannot occur in practice? If the "casting table" also   
included sub-classes of the data types(e.g that casting to/from a xs:NOTATION   
derivation) it would to me make sense, but I don't see how it does that.   
Considering that one user(me) is at least confused, the formerly mentioned  
paragraph could perhaps be deepened a bit.    
Comment 1 Michael Kay 2005-06-29 22:27:01 UTC
Yes, we probably need to explain this better. Casting to subtypes of xs:NOTATION
is allowed, but the standard mechanism of casting across to xs:NOTATION and then
down to the subtype doesn't really work here.

Michael Kay
Comment 2 Ashok Malhotra 2005-07-12 21:25:26 UTC
The WGs decided on the joint call on July 12, 2005 to add wording to section
17.1 of the F&O to clarify that casting is not permitted from xs:NOTATION to
xs:NOTATION, since it is an abstract type, although it is permitted from one
subtype of xs:NOTATION to another.  The entry in the table at the intersection
of xs:NOTATION and xs:NOTATION should be changed to "M".