Referencing Parameters and Variables
You refer to parameters or variables in mashup scripts within XPath expressions or in dynamic mashup expressions in the form:
$parameter-or-variable-name
Note: There is one exception to this rule. For the inputparameters property of <invoke>, omit $ and use just the variable or parameters names.
This is also true for variables that you declare implicitly.
In this first example, an existing parameter or variable named variableA is used in an XPath expression to assign a portion of this variable to a new, implicitly declared variable named implicitVar.
The second example simply refers to an existing input parameter, inputParamA, and an existing variable, declaredVariable.