With ODS-5 enabled, RMS can manipulate filenames and subdirectory
    specifications of up to 255 8-bit or 16-bit characters in length.
    RMS can handle a total path name 512 8-bit or 16-bit characters
    in length.

    Prior to OpenVMS Alpha Version 7.2, the NAM block interface could
    pass file specifications of up to 255 bytes each (including the
    resultant file specification). The following topics describe the
    changes that allow for passing longer file specifications and
    that provide compatibility with applications using the NAM block
    interface prior to this release.