Used carefully simply macros are a powerful concept, but they can be abused. Advanced Macros Macros can also be defined with parameters. This can be used in more complex situations. In fact the implementation defines the arguments as simple macros. There may be up to 5 arguments, and the names can be any choice of letters.
Case is significant in macro names.
When writing a complex score it is sometimes all too easy to forget to what the various instrument numbers refer. One can use macros to give names to the numbers. It is sometimes convenient to have the score in more than one file. For most uses the double quote symbol will probably be the most convenient. This takes input from the named file until it ends, when input reverts to the previous input.