4GL/GX calls to C programs?

We are considering purchasing 4GX in order to create a "GUI-looking" front end. I have received a few questions regarding 4 GL/GX that were passed on to me from our developers: 1) Does 4 GL/GX have the capability to connect to our existing C programs? Specifically, after selecting data from the database, we want to send the selected data to a function. This means that our interface needs to allow us to link our C programs in a compile time. Can 4 GL/GX do this? How? 2) Will we be limited in the number of C routines used? (There are not many, maybe 5 to 10). What are the performance/design considerations/concerns? 2) Does 4GL/GX require any additional products like ESQL-C in order to link it in with our applications? What other products can 4GL/GX use? Can C-ISAM be used? Thanks in advance, Andy Mikesell Andy_Mikesell@mail.amsinc.com (303) 989-7065