/sys$common/syshlp/helplib.hlb LBR Routines, LBR$GET_HEADER, Description  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    On successful completion, LBR$GET_HEADER places the library
    header information into the array of 128 longwords.

    Note that the offset is the byte offset of the value into the
    header structure. You can convert the offset to a longword
    subscript by dividing the offset by 4 and adding 1 (assuming
    that subscripts in your programming language begin with 1).