VMS Help System Services, $SETEXV  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Assigns a condition handler address to the primary, secondary, or
    last chance exception vectors, or removes a previously assigned
    handler address from any of these three vectors.

    Format

      SYS$SETEXV  [vector] ,[addres] ,[acmode] ,[prvhnd]

    C Prototype

      int sys$setexv  (unsigned int vector, int

                      (*addres)(__unknown_params), unsigned

                      int acmode, void *(*(prvhnd)));

1 - Arguments

 vector

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Vector for which a condition handler is to be established or
    removed. The vector argument is a longword value. The value
    0 (the default) specifies the primary exception vector; the
    value 1, the secondary vector; and the value 2, the last chance
    exception vector.

 addres

    OpenVMS usage:procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by reference
    Condition handler address to be established for the exception
    vector specified by the vector argument. The addres argument is
    a longword value containing the address of the condition handler
    routine.

    If you do not specify addres or specify it as the value 0, the
    condition handler address already established for the specified
    vector is removed; that is, the contents of the longword vector
    is set to 0.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode for which the exception vector is to be modified.
    The acmode argument is a longword containing the access mode. The
    $PSLDEF macro defines symbols for the four access modes.

    The most privileged access mode used is the access mode of the
    caller. Exception vectors for access modes more privileged than
    the caller's access mode cannot be modified.

 prvhnd

    OpenVMS usage:procedure value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Previous condition handler address contained by the specified
    exception vector. The prvhnd argument is the address of a
    longword into which $SETEXV writes the handler's procedure value.