Macros can be used in both action and export code. Within the macro's stored code, calling argument values are inserted using a $-number that reflects the sequence number of the argument supplied in calling code.
Consider a macro named "Hello" that has this stored code:
"Hello $1!"
When using the 'Hello' macro in code, it is called like this:
$MyString = do("Hello","Cubert"));
which inserts the argument value 'Cubert' into the macro code at the position $1. The result is the output of the macro passed to $MyString is "Hello Cubert!".