Intermec PC4 Programmer's Reference Manual page 122

Chapter 4 — ESim Commands
Remarks: The reference point command is used to establish top and left
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margins to prevent printing off the edge of the label. A minimum
margin of 1 mm should be used on all sides of the label.
Repeated printing outside the edge of the media can
cause excessive printhead wear.
For narrow labels, the R command could be substituted by q and r
commands, which have the benefit of making better use of a limited
image buffer. Any R command after a q command resets the width to
the maximum print width, as a q832 command. The values for the
latest R command (or r, whichever was last executed) are printed on
the test label.
The print direction commands ZB, and ZT affect the location of the
reference point, as illustrated below.
Reference Point Example
ESim for the PC4 and PF8 Printers Programmer's Reference Manual