C and 4gl

Hi, I am writing C functions which are to be called from Informix-4gl and I am using popint(), popquote() etc. to retrieve arguments off the 4gl stack. The problem with this is that you need to know the type of each argument in advance in order to know which popXXX() function to call. In Informix-3.3 screens and reports you were given perfvalues and acevalues which contained both data and the type of that data; If 4gl had something like this it would solve my problem. In my situation it is not OK to just use popquote() with a sufficiently large buffer with the understanding that 4gl can convert almost any type into a string. I really do need to know what the types are. Any suggestions??? Thanks in advance, Greg