Extended_File_Names

   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.