In addition to the exceptions from examination in the classified postal
service made by Postal Rule II, clause 5, the following exception to
examination in that service is hereby made:
Printers, employed as such.
_Provided_, That before any person may be employed under this
exception to examination the Post-Office Department shall inform the
Commission of the authority given to employ printers at any post-office
and of the number authorized to be employed at such office.