HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part I

12-4 Macros EN
Macros occupy a portion of user memory. The number of macros that
can be stored simultaneously in user memory is limited only by the
amount of available user memory.
Macro Invocation
There are three ways to invoke a macro: execute, call, and overlay,
using the Macro Control command.
When a macro is executed, it begins performing its commands using
the current modified print environment. Changes made to feature
settings during macro execution are recorded in the modified print
environment; these changes are retained upon completion of the
macro execution.
When a macro is called, it begins performing its commands using the
current modified print environment. Before the macro is performed,
the current modified print environment is saved. Changes made to
feature settings during a macro call are recorded in the modified
print environment; however, these changes are not retained upon
completion of the macro call. The modified print environment that
existed prior to the macro call is restored.
When a macro is enabled for automatic overlay, its execution is
the final operation each time a page is printed. Before the macro
is performed, the current modified print environment is saved and
replaced with the overlay environment. The overlay environment
is a combination of the user default and the current modified print
environments. Changes, made to feature settings during macro
overlay, are recorded in the modified print environment; however,
these changes are not retained upon completion of the macro overlay.
The modified print environment that existed prior to the macro overlay
is restored.
Note HP-GL/2 commands are not supported within macros on all
HP LaserJet printers. Refer to the “PCL Feature Support Matrix”
in Chapter 1 of the PCL 5 Comparison Guide for specifics.