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Evaluates whether a variable by some name has been initialised or not.

Returns a boolean.

variable:IsDefined( xpath >> string )

The return value is true if a variable by the name of string has been initialised, and otherwise false.


A variable may be initialised and have the empty string ( '' ) as a value. The result of the following is true:

<pc:assign-string-default rdbms="" />
<pc:assign-boolean isdefined="{variable:IsDefined('rdbms')}"/>
<pc:value-of select="$isdefined"/>