Thanks to everyone who contributed. I am now clear that COMPILE LONG IF will only accept a constant. I went back and had a look at Staz's AppleEvent filter, and he places a constant in a separate GLBL file which is looked at before all the other Globals, so he can use COMPILE LONG IF throughout the program. BTW, thanks Tedd for your input - I just misunderstood what you were suggesting. You way would work, but leaves the code in the final application, thus increasing its size. I was trying to reduce the executable size, is all. The program's already 2Mb and is still growing by the hour. Phil.