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[Bug 1616] New: only the semantics of sequence types are specified, not all formal types

From: <bugzilla@wiggum.w3.org>
Date: Fri, 15 Jul 2005 00:23:09 +0000
To: public-qt-comments@w3.org
Message-Id: <E1DtDyv-0005RN-7v@wiggum.w3.org>


           Summary: only the semantics of sequence types are specified, not
                    all formal types
           Product: XPath / XQuery / XSLT
           Version: Last Call drafts
          Platform: PC
        OS/Version: Windows 2000
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Formal Semantics
        AssignedTo: simeon@us.ibm.com
        ReportedBy: fred.zemke@oracle.com
         QAContact: public-qt-comments@w3.org

2.4.1 XML Schema and the [XPath/Xquery] type system
Many possible formal type notations do not appear to have any
defined semantics.  For example, I have been
trying to determine the semantics of "document{empty}",
which presumably would describe a 
document node with no children, so that 
"dynEnv |- document {} : document { empty }"
should be inferable, but I have not found any rules to make such
an inference.  Similarly, the semantics 
of document { element p:o? }, document { element p:o+ }
and document {element p:o *} seem to be undefined.
I saw the statement in section 2.4.2 "Item types" that
"The semantics of sequence types is described in [3.5.4 Sequence
Type Matching]".  However, 3.5.4 does not provide any 
semantics for document{empty}.  Re-examining the quoted sentence,
I see that it only says that the semantics of 
sequence types is specified in section 3.5.4.  Presumably
"sequence type" is the same as "SequenceType". (As a lesser issue,
this should also be clarified; the specification should not 
assume that similarly spelled terms mean the same thing.) 
Back to the main issue, the formal type 
notations are deliberately designed to be a superset of the 
sequence types, so it seems to be a deficiency, that the semantics
of the formal type notations is only specified when a formal
type notation is one that would have been derived by normalizing
a sequence type.  

(The difference between this comment and #1615 is 
that #1615 questions whether you really 
mean to support document { Type }, whereas this comment 
questions whether formal types that are not sequence types
have any specified semantics.)
Received on Friday, 15 July 2005 00:23:11 UTC

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