Information request - totaly, totaly OT

[naamagatus]

Hi,

I aplogise for taking space for this purely personal request, but I've spent the last two 
hours scouring the net for a clear definition. So, I thought - there are so many clever 
people here (only the best butter, you notice!), someone must know, and maybe they won't 
mind helping. 

SO - what the ... is an 'action system'?! It pops up in a lot of contexts, mainly I think 
in programming? But I need a general definition, since it's a term I ran against regarding 
Talcott Parsons (sociologist).  

Any help will be much appreciated!

Naama