Re: Does it make sense to have a default with a nillable element?

[ht@markup.co.uk (Henry S. Thompson)]

"Costello, Roger L." <costello@mitre.org> writes:

> The following XML Schema declares an element to be nillable and the element has a default value:
>
> <xs:element name="test" type="xs:string" nillable="true" default="Hello, world" />
>
> That is legal but is it meaningful?
>
> What does this (schema-valid) XML instance mean:
>
> <test xsi:nil="true"></test>

What does it mean?  XML Schema doesn't have answers to such
questions.  What does the PSVI say?  It says

 ·absent· <#key-null>

Why?  Because it says so here [1]:

  *PSVI Contributions for element information items*

   [schema normalized value] 
    The appropriate case among the following:
     1 If the element information item is not ·nilled· ...
     2 Otherwise ·absent· <#key-null>

   [schema actual value]
    If the [schema normalized value] is not ·absent·, then ...;
     otherwise ·absent·

ht

[1] https://www.w3.org/TR/xmlschema11-1/#sec-sic-eltType
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		    Henry S. Thompson, Markup Systems Ltd.
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