NAME
        CallHookA -- Invoke a hook given a pointer to a message.

   SYNOPSIS
        result = CallHookA( hookPtr, obj, message )

        ULONG CallHook( struct hook *, object *, aptr );

   FUNCTION
        Invoke a hook on the supplied hook-specific data (an "object")
        and a parameter packet ("message").  This function is equivalent
        to utility.library/callhookpkt().

   INPUTS
        hookPtr - A system-standard hook
        obj - hook-specific data object
        message - The hook-specific message you wish to send

   RESULT
        result - a hook-specific result.

   NOTES
        This function first appeared in the V37 release of amiga.lib.
        However, it does not depend on any particular version of the OS,
        and works fine even in V34.

   SEE ALSO
        callhook(), utility.library/callhookpkt(), <utility/hooks.h>