I am currently developing a set of applications in C under MPE.

This software will need to have approximately 150
variations for different clients.  These variations will be
small (say - 1% of the entire application).

The approach I have taken is to have 1 main program where 99%
of the code resides, and a small executable library (XL) for each
client.  The XL will have 1 function - Custom() containing all
of the client specific code.

I will always be running the same program, but linking in a
different custom XL at runtime.

run mainprog;xl="custom1.xl"
run mainprog;xl="custom2.xl"
run mainprog;xl="custom3.xl"
etc

This is working, but now my problem:
Once I am inside the Custom() function in the XL I would like to be
able to call functions back in the mainprog.

I cannot get this to work, because any attempt at calling a function
in mainprog results in an unresolved external.  I understand why I am
getting this, but is there any way to get this to work?

Any comments, ideas, or suggestions would be appreciated.


Ken Hood
Trans Union of Canada
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