variable(name,value)
Declares a local variable having specified name in a macro. Initializes local variable to specified value. Parameter name is a string representing an XML qualified name.
It's an error to use variable() outside a macro.
Example:
set-variable("v1", 0);
macro m1() {
    (: Local to macro m1. Shadows global variable v1. :)
    variable("v1", 1000); 
    set-variable("v1", $v1 + 500);
    if ($v1 != 1500) {
        error("FAILED");
    }
}
if ($v1 != 0) {
    error("FAILED");
}