In the past, when you zoomed into a part of the work area, PTC ALD had to recalculate and redraw windows. The internal macro wrc was used for this. Thewzw macro was called to warn the rest of the system that a zoom had taken place so the current document could be reformatted and redrawn. Now the recalculating and redrawing is done a different way and the wrc:wzw sequence is only used when you really change the underlying scale used by PTC ALD via the scale macro.