Memptr or character parameters?

Here is an alarming e-mail from Brent Wardle to the Peg. (I know one should no copy e-mails from one forum to antoher, but this one really needs attention in the context of this website).
Hi Peg,
We are upgrading from 9.1D to 10.B and I found an issue tonight that you
may or may not know about.
You can no longer define and use a character output parameter for a
windows DLL call.
You do not get an error message during compile but at run time you get:
"You cannot use OUTPUT to return CHAR or LONGCHAR data. Use MEMPTR
Instead (12200).
Error 12200 is not available on KB error code search.
This impacts some of the DLL calls used in things like GetHostName.p
which is/was used in smtpmail.p and other deadline saving / FFW code.
Calls like:

PROCEDURE gethostname EXTERNAL "wsock32.dll" :
  DEFINE INPUT        PARAMETER p-Length        AS LONG.
  DEFINE RETURN       PARAMETER p-Return        AS LONG.

Cause the error.
p-Hostname must now be a MEMPTR and must be sized before and cleaned up
after the call.
Not sure if this impacts Unix/Linux shared lib calls.