What's a system call ( Was: 'what' doesn't use perror...)

[Guy Harris]

>Actually, a system call is an entry point which is a one-for-one mapping to a
>particular kernel service.  Open(2) is a system call which returns a file
>descriptor, which is a kernel data structure. 

On *some* implementations of the UNIX system interface, "open" is a
system call which returns a file descriptor, which is a kernel data
structure.  I don't think it is in Apollo's DOMAIN/OS (or is that
"Domain/OS"?) implementation, for example.