VMS Help System Services, $GOTO UNWIND (Alpha Only), Arguments  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 target_invo

    OpenVMS usage:invo_handle
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    The address of a location that contains a handle for the target
    invocation.

    If you do not specify the target_invo argument, or if the handle
    value is 0, an exit unwind is initiated.

 target_pc

    OpenVMS usage:address
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference
    The address of a location that contains the address at which
    execution should continue in the target invocation.

    If the target_pc argument is omitted or the value is 0, a system-
    defined target PC is assumed and execution resumes at the
    location specified at the return address for the call frame of
    the target procedure invocation.

 new_r0

    OpenVMS usage:quadword_unsigned
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference
    The address of a location that contains the value to place in the
    saved R0 location of the mechanism argument vector. The contents
    of this location are then loaded into the processor R0 register
    at the time that execution continues in the target invocation.

    If the new_r0 argument is omitted, the contents of the processor
    R0 register at the time of the call to $GOTO_UNWIND are used.

 new_r1

    OpenVMS usage:quadword_unsigned
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by reference
    Address of a location that contains the value to place in the
    saved R1 location of the mechanism argument vector. The contents
    of the location are then loaded into the processor R1 register at
    the time that execution continues in the target invocation.

    If the new_r1 argument is omitted, the contents of the processor
    R1 register at the time of the call to $GOTO_UNWIND are used.