Francois Thunus wrote in a message to Mike Bilow:

 FT> why, and what difference exactly do you make between PM and WPS 
 FT> ? I thought WPS was just a subset of the older PM library ?

PM and WPS are very separate.  You can even start PM without starting WPS
by editing your CONFIG.SYS file, and I know several people who do this.

PM encompasses the support necessary for drawing all graphical objects onto
the screen, and it presents the various APIs for accessing these services. 
PM was originally introduced in OS/2 1.1, although it has undergone major
changes.

WPS is a special kind of PM application, but just an application.  It
provides the object-oriented framework that the user sees, integrates SOM
over PM, and does a number of other useful but not essential things.
 
-- Mike


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