Rob Landley wrote in a message to Tony Belding:

> dgroup?  What is a dgroup?

 RL> Old dos limitation that doesn't apply to OS/2.

DGROUP is still significant, although essentially trivial, in flat model. 
By definition, DGROUP is the range of memory spanned by the selector loaded
in the DS register at program startup.  In OS/2 32-bit flat model, DS, ES,
and SS are all guaranteed to contain the same selector at startup, and the
range of memory addressed by that selector is DGROUP.

Note that some process memory may not be in DGROUP even in 32-bit flat
model, particularly code space addressed by the selector in CS.  Casting a
function pointer for use as a data pointer, although perfectly legal in C,
may cause trouble if done by an OS/2 application.
 
-- Mike


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