pc

    OpenVMS usage: PC value
    type:          quadword (unsigned)
    access:        read only
    mechanism:     by value
    Input quadword, target PC (that is, the PC for a code region the
    user wants unwind information for).

 get_ue_block

    OpenVMS usage: unwind_entry_data_block
    type:          quadword (unsigned)
    access:        write
    mechanism:     by reference
    Address of a 4-quadword block to be filled in. That is, input the
    address of a 4 quadword block and, on successful returned status,
    that block will be updated with the following information:

    o  code_start_va - Output quadword, the process virtual starting
       c unwind region containing the input IP.

    o  code_end_va - Output quadward, the process virtual ending code
       address of the unwind region containing the input IP.

    o  uib_start_va - Output quadword, the process virtual address of
       the UIB for the unwind region containing the input IP.

    o  gp_value - Output quadword, the GP value for this code region.

 name

    OpenVMS usage: pseudo-image-name
    type:          character-code-text-string
    access:        modify
    mechanism:     by descriptor-fixed-length string descriptor
    Optional, that is, may be zero. If the name parameter is
    specified and if a name was registered for the unwind region,
    then the descriptor pointer and length are updated to point to
    that stored name. Note that if the name parameter is specified
    but no name exists in the unwind tables, then the name descriptor
    is updated to zero length.