RTN_SUCCESS macro

[npr@jach.hawaii.edu (Nick Rees)]

I am still getting to grips with Epics status values. I have been using
the RTN_SUCCESS macro and today wanted to find out what it meant. I
found the following in errMdef.h:

#define RTN_SUCCESS(STATUS) ((STATUS && 1)==0)

Does this mean what I think it means - i.e. !STATUS (or STATUS == 0) ?

or should the && be a bitwise & ?

or is it a C construct to do something more clever? (By opening my mouth
I may be exposing myself as not being a C afficionado.)

Nick