HP PCL/PJL reference - PCL 5 Comparison Guide

2-80 Printer-Specific Differences ENWW
Note PCL objects stored on the printer disk cannot be deleted, set to
temporary, set to permanent, or modified in any way using the PCL
language.
21 Deletes the macro association named by the current Macro ID. The
macro must have been associated with an alphanumeric Macro ID
(using operation 4). No String ID is supplied (
?&n1W21). This
command removes the alphanumeric macro name association, however
the disk resource itself is not changed.
100 Media select (see media selection table). Media types are specified
using the printer control panel. The following table indicates which
media type and paper size is used in the various media-select
situations.
Operation Description