Given
<xsl:variable name="datePrecision" as="element()*">
<p>Year</p>
<p>Month</p>
<p>Day</p>
<p>Time</p>
<p>Timestamp</p>
</xsl:variable>
The expression
$datePrecision[5]
returns a nodeSet containing one text node with value "Timestamp", as expected.
Later in a template, with a context element having an attribute
@precision="5"
I try the following expressions but all return an empty string:
$datePrecision[@precision]
$datePrecision[number(@precision)]
$datePrecision[xs:decimal(@precision)]
However, the following sequence does what I want
<xsl:variable name="prec" select="number(@precision)"/>
... $datePrecision[$prec] ...
Using Oxygen/XML's debugger I've stepped to the point where the expression is about to be evaluated and display the following in the watch window:
Expression Value Nodes/Values Set
-------------------------- --------------- -----------------------
$datePrecision[5] Node Set(1) #text Timestamp
@precision Node Set(1) precision 5
$datePrecision[@precision]
number(@precision) 5
$datePrecision[number(@precision)]
$prec 5
$datePrecision[$prec] Node Set(1) #text Timestamp
Obviously I've missed something fundamental about how attribute nodes are atomized for use in a predicate, but can't find anything in the docs (Michael Kay's XSLT/XPATH 2.0, 4th ed) that would explain this difference.
Can someone explain why this is occurring, and point me to where, in either the XSLT 2.0 spec or Michael Kay's book, where this is described?
(the XSLT processor is Saxon-PE 9.2.0.3)