Variable in xsl:template matching pattern

Question

Given

An XSLT stylesheet with a global variable:

Answer 1

Variables are not allowed to be used in match expressions in XSLT 1.0.

From the XSLT 1.0 specification: Defining Template Rules

It is an error for the value of the match attribute to contain a VariableReference.

Variables are allowed in match expressions in XSLT 2.0.

From the XSLT 2.0 specification: Syntax of Patterns

Patterns may start with an id FO or key function call, provided that the value to be matched is supplied as either a literal or a reference to a variable or parameter, and the key name (in the case of the key function) is supplied as a string literal. These patterns will never match a node in a tree whose root is not a document node.