>If you are only going to call it once then perhaps you dont need too use macros at all or perhaps you dont need to have >the second macro A.

OK, now what about this? So I need to call %a inside %main multiple times in more than one looping.

I guess my question now is that for structure 2, if I only call %main once, does %a get compiled many times? Or just once like since it is before any of the looping?

Structure 2:

%macro main;

%macro a; ... %mend a;

...

%do i=1 %to &xx; %a %end;

...

%do i=1 %to &yy; %a %end;

%mend main;