To use a macro from inside a program, just state its name with a "." tacked
onto the beginning, as in

me @ .foo notify

To define a macro (the syntax isn't advertised anywhere):

say

def <macro-name> <macro-definition>

macro-name is one word, no spaces.  Everything after the space after macro-name
will be taken to be the macro-definition.

Macros cannot be renamed/redeffed, but can be killed. Only a wiz can kill
them.

They are stored in a binary tree which is dumped into the file muf/macros at
dump time, and which is rebalanced at db load time.