process_id

    The child process or set of child processes.

 status_location

    A pointer to a location that contains the termination status of
    the child process as defined in the <wait.h> header file.

    Beginning with OpenVMS Version 7.2, when compiled with the _
    VMS_WAIT macro defined, the waitpid function puts the OpenVMS
    completion code of the child process at the address specified in
    the status_location argument.

 options

    Flags that modify the behavior of the function. These flags are
    defined in the Description section.