xmacro: is used to delete the definition of a macro name from the RFPP macro
table. It is a selective purge operation.
Syntax:
xmacro:([macro-name])
macro-nameis the macro to be purged. The function of the surrounding square
brackets is to 'protect' the name from being replaced by its definition.The use
of square brackets is detailed in the section called “Defining Macros”.
