Most any line not starting with a digit is a comment, see manual for exceptions
06keydef .vi
07source /usr/local/80col\n
08source /usr/local/132col\n

I use my function key 10 for temporary, repetitive things; complicated
commands, sequences, etc. Real nice if application allows shell escapes.
Most often used with complicated vi commands. 
09keydef 10\n

Function key 11 may default to 'esc' but you can override it here
11^[
12#include <
13#define\t
14\nmain(argc,argv)\n   int    argc;\n   char **argv;\n{\n

15apropos 
16mount /dev/ra3a /src;su sccs;cd

A word I often need but can never spell
17Albuquerque

An example of a shell escape, normally used to sleep for one second (see man)
!echo "shell escape"

Some vi commands
18 ^[:/\n:s\n
19 ^[:w\n
20^[:!soundslike 

Now the hard part is remembering which key is what, especially if you
maintain several .keydef* files.
