>>Declared PRIVATE in the main program does allow it to be available throughout the app. Or make it a project level property on an object. You could even call it oProject.Constants.My_Constant if you wanted.
>
>This leads us to another interesting point. Variables and properties can be changed. The defined constants can only be re-defined using #UNDEF directive first.

Someone else said that too. It was the only point that I've seen so far that gave the DEFINE any real value to me, but I don't know if it's enough to use them instead of variables. If there are a couple hundred variables in your code, what's adding 20 more? I would rather have them all defined in the same place anyway.