Sometime one wants to merge set elements from several GDX-files into one basic set. Below is code fragment, which shows how to o this, even if the gdx-files files contain lots of common elements.

First we generate some gdx files:

set a /a,b,c/;
set b /c,d,e/;
execute_unload "seta",a;
execute_unload "setb",b;

Now we combine these gdx files into one:

set c;
$onmulti
$gdxin seta
$load c=a
$gdxin setb
$load c=b
display c;

which gives:

   1  set c;
--- LOAD  c = 1:a
--- MERGE c = 1:b
   7  display c;

----      7 SET c

a,    b,    c,    d,    e