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

EN RO, Rotate Coordinate System 19-37
Figure 19-16 shows the locations of P1 and P2 when you follow the
rotation with the IP command.
Figure 19-16Using IP after the RO Command
When you set-up a soft-clip window (see the IW command), RO
also rotates the window. If a portion of a window rotates outside the
hard-clip limits, it is clipped. Note that IP does not affect the window
limits. Use IW to reset the window to the size of the PCL Picture
Frame.