VMS Help TCPIP Services, Programming Interfaces, Sockets API, select(), Errors  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    EBADF              One or more of the I/O descriptor sets
                       specified an invalid file descriptor.
    EINTR              A signal was delivered before the time limit
                       specified by the timeout argument expired and
                       before any of the selected events occurred.
    EINVAL             The time limit specified by the timeout
                       argument is invalid.
                       The nfds argument is less than zero, or
                       greater than or equal to FD_SETSIZE.
    EAGAIN             Allocation of internal data structures failed.
                       A later call to the select() function may
                       complete successfully.
    ENETDOWN           TCP/IP Services was not started.
    ENOTSOCK           The socket descriptor is invalid.