title: Use Alex macros from another file
body: <p>Is there any way to have an Alex macro defined in one source file and used in other source files? In my case, I have definitions for <code>$LowerCaseLetter</code> and <code>$UpperCaseLetter</code> (these are all letters except <code>e</code> and <code>O</code>, since they have special roles in my code). How can I refer to these macros from other <code>.x</code> files?</p>