fopen ( ..., "a" ) --- how does the "a" work?

[Doug Gwyn]

In article <3263 at hub.UUCP> 6600pete at hub.UUCP writes:
>Perhaps the best way to do it, then, is to call open() with O_APPEND,
>then pass the handle to fdopen()? What does anyone think?

I think you haven't shown us a clear conception about what you
need to do.  Is there some reason for not using fopen(...,"a")
and letting the C implementation worry about the details?