While I was working on the macro processor, I noticed that many of the uses of the macro processor I found around the Internet also used MATRIX...END MATRIX, so I decided to work on that next.
I've made significant progress. I now have implemented the most important parts of the matrix language. Over the coming weeks, I'll work on the rest. If anyone has examples of the use of the matrix language, please send them along so I can make sure that they're supported.