VFLUSH vs. VDISCARD

[markus%gyger.org@localhost (Markus Gyger)]

[SSH-CONNECT] mentiones in Encoding of Terminal Modes:

15    VFLUSH      Character to flush output.
[...]
18    VDISCARD    Toggles the flushing of terminal output.

There are systems that simply  #define VDISCARD VFLUSH
and also treat  stty flush ^o  and  stty discard ^o  the
same. Are there implementations where they are distinct?

SUSv3 only informatively mentions VDISCARD as reserved:
http://opengroup.org/onlinepubs/009695399/basedefs/termios.h.html#tag_13_74_04


Markus