[Bug 8217] New: [XSLT] Confusing text on function conversion rules for sequence constructors

http://www.w3.org/Bugs/Public/show_bug.cgi?id=8217

           Summary: [XSLT] Confusing text on function conversion rules for
                    sequence constructors
           Product: XPath / XQuery / XSLT
           Version: Recommendation
          Platform: All
               URL: http://www.w3.org/TR/xslt20/#dt-function-conversion-
                    rules
        OS/Version: All
            Status: NEW
          Severity: trivial
          Priority: P5
         Component: XSLT 2.0
        AssignedTo: mike@...
        ReportedBy: zongaro@...
         QAContact: public-qt-comments@...


A colleague pointed out the following potentially confusing text to me.
According to section 5.3 of XSLT 2.0,[1] "Except where otherwise indicated, the
actual value of an expression is converted to the required type using the
function conversion rules....  The relevant rules are those that apply when
XPath 1.0 compatibility mode is set to false."

The following paragraph then says, "This specification also invokes the XPath
2.0 function conversion rules to convert the result of evaluating an XSLT
sequence constructor to a required type (for example, the sequence constructor
enclosed in an xsl:variable, xsl:template, or xsl:function  element)."

Reading that, one might easily be lead to believe that when the function
conversion rules apply to an expression, only the rules with compatibility mode
set to false apply, but when they apply to a sequence constructor, the setting
of the compatibility mode for the sequence constructor is taken into account.

The only clue that compatibility mode of false always applies for sequence
constructors too is the fact that the words "function conversion rules" in that
second paragraph have a hyper-text link to the preceding paragraph.

To avoid confusion, I would suggest adding the following sentence after "or
xsl:function element)":  "Again, the relevant rules are those that apply when
XPath 1.0 compatibility mode is set to false."

[1] http://www.w3.org/TR/xslt20/#dt-function-conversion-rules


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http://www.w3.org/Bugs/Public/show_bug.cgi?id=8217





--- Comment #1 from Michael Kay <mike@...>  2009-11-06 14:51:22 ---
A better fix might be to make the definition into a real definition, and add a
clarifying note: change

[Definition: Except where otherwise indicated, the actual value of an
expression is converted to the required type using the function conversion
rules. These are the rules defined in [XPath 2.0]  for converting the supplied
argument of a function call to the required type of that argument, as defined
in the function signature. The relevant rules are those that apply when XPath
1.0 compatibility mode  is set to false.]

to

[Definition: When used in this specification without further qualification, the
term <term>function conversion rules</term> means the function conversion rules
defined in [XPath 2.0], applied with XPath 1.0 compatibility mode set to
false.]

Note: These are the rules defined in [XPath 2.0] for converting the supplied
argument of a function call to the required type of that argument, as defined
in the function signature. The same rules are used in XSLT for converting the
value of a variable to the declared type of the variable, or the result of
evaluating a function or template body to the declared type of the function or
template. They are also used when parameters are supplied to a template using
<xsl:with-param>. In all such cases, the rules that apply are the XPath 2.0
rules without XPath 1.0 compatibility mode. The rules with XPath 1.0
compatibility mode set to true are used only for XPath function calls, and for
the operands of certain XPath operators.


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