SUPP.h	- Contains a support function (used by the function in OUT.c).
VARS.h	- Contains the definition of the Structure, the I/O Variables (at locations 0xf002) and the bit.

You should not define any code nor data in a header file; you should only declare them!

If you really are defining functions & variables, this will certainly give you lots of errors due to duplicate definitions

If you don't understand the difference between definitions and declarations, use the 'Search' button - I've covered it before!