System V -- Information on /usr/lib/cron/.proto

[M. D. Parker]

In observing the operation of 'at', I have noticed that it places information
from the /usr/lib/cron/.proto file at the head of the job.  I would 
be interested in knowing what variables are passed for integration into
this file.  From what I see, there is $d for local directory, and $l for
limit.  How many other such variables are provided?  What are their names
and functions?

Thanks again for your help.

Mike Parker
Manager, Systems Administration