Hi everyone again, I've coded some test programs that I now want to merge into one program. I'm reading up on how to use the SUBROUTINE definitions and how to pass variables between subroutines, however there's one thing in particular that I don't know how to deal with. Where do I put the include statements? All my subroutines need to use an include .h file. I've read that when compiling, you need to put the subroutine files first with your main handler program last. I'm using iFort to compile and my command to compile is as follows, is this correct: ifort test_subroutine.f90 test_main.f90 -o test.e Any help would be really appreciated!!