I think his talking about function parameters.
Do it just like that:

Code:

---

function main()
{
   test_sub(30);
   temp = 20;
   test_sub(temp);
}

function test_sub(a)
{
   //after thrist call a == 30
   //after second call a == 20
   ...
}

---

This is NOT possible with actions!!! For actions you have to use global Variables.
For more informations about parameters look into the manual.

Dark_Samurai