What does it mean to have pz on a pentax lens?

PZ on the lens should not have the same meaning as the body number. It is the abbreviation of Power zoom, which means super electric zoom. It is a unique function of PENTAX lenses (but Canon and Minolta also have one or two This type of lens) can be used with all Z and MZ series bodies (except D_SLR). If used with Z-1P, it can also have tracking zoom and radial zoom functions. However, many people think that this function is of little use and also consumes a lot of electricity.

You can refer to the explanation of this photography term:

AF POWER ZOOM is an electric automatic drive focus, electric zoom SLR lens. In the early 1980s, various manufacturers developed this type of lens. Due to its large size and high power consumption, there were no follow-up products and it faded out of the market. Now it is only widely used in lightweight rangefinder machines.

This is also mentioned, you can take a look:/print.php?f=164&t=158183&p=1