This document gives a summary of all the calibration corrections applied
to individual PSPC events during their conversion from their
arrival position & pulse height (PH) channel to their
corrected coordinates & pulse-invariant (PI) channel.
This memo is essentially a copy of the original MPE memo
TN-ROS-ME-ZA00/027 (Hasinger & Snowden, 1990), but updated and expanded
to refer to the FITS versions of the calibration files available from