The code generated by a macro definition called by an inner macro call is nested inside the code generated by the macro definition that contains the inner macro call. In the macro definition called by an inner macro call, you can include a macro call to another macro definition. Thus, you can nest macro calls at different levels.

The &SYSNEST system variable indicates how many levels you called. It has the value 1 in an outer macro, and is incremented by one at a macro call.