Application Area in GCX2 TCode for Client-Specific User Exit maintenance

Hi All,

I am basically an ABAPer trying to understand some basic aspects of FI module.

In order to implement validations for FI postings as per Customers requirement, we can create User Exits and maintain them in GCX2 TCode (T80D table).

In this TCode, we have to maintain an Application Area mapped to a Program Name which contains the customized validations.

My question is, What do we mean by an Application Area. In the R/3 box that I work in, I can see an Application Area called GBLR which has a program mapped to it. This program has capability of validating certain fields while FB70 and FB75 postings.

Please help me understand the concept of Application Area in this regard.

Thanks and Regards,

Subhrangsu