Workplace Shell

It is based on Common User Access and made a radical shift away from the Program Manager type interface that earlier versions of OS/2 shared with Windows 3.x or the application-oriented WIMP interface of the Apple Macintosh.

Although mostly written in C, under the covers the Workplace Shell is implemented as an object-oriented class library, basing on the System Object Model (SOM).

SOM and its IDL was developed by IBM in their Austin, Texas lab.

The classes can easily be manipulated by sending simple settings strings (like "KEYWORD=VALUE;") to them both via a C and a Rexx API.

This allows for many useful third-party desktop utilities that add or modify functionality to or of existing objects without access to IBM's source code.