>> >  http://www.w3.org/TR/2007/REC-xpath20-20070123/#id-castable
>> >  "[if] the input argument of the expression is of type xs:string but it
>> > is
>> >   not a literal string, the result of the castable expression is false."
>>
>> To help me understand that :-)
>
> Not a problem, Andrew ... I get asked about this terminology in the
> classroom.
>
>> can you provide an example of a user
>> constructed string that is not a string literal?
>>
>> For example, tokenizing a string into a sequence of strings... they
>> are all string literals aren't they?
>
> Nope ... a string literal is "literally a string in the stylesheet" written
> with string delimiters.  The term "literal" here is in reference to the
> XPath written syntax.
>
> A sequence of strings is just that: a sequence of string values in memory.
>
> A literal string in the stylesheet is just that:  a string value literally
> delimited in the stylesheet.  See production 74 of the XPath syntax:
>
>  http://www.w3.org/TR/2007/REC-xpath20-20070123/#doc-xpath-StringLiteral
>
> The difference is a syntax issue:  a string literal is a type of primary
> expression (production 41) written in the stylesheet syntax and it is the
> way to represent a string value in the XPath syntax different from the
> representations of other literal values.
>
> I hope that clarifies the distinction.

It does, thanks Ken.

Doesn't that restriction then make "castable as xs:QName" pretty
useless?   I can't see when you would need it...




--
Andrew Welch
http://andrewjwelch.com
Kernow: http://kernowforsaxon.sf.net/