The Free On-line Dictionary of Computing (30 December 2018):

Binhex 4.0

    A seven bit wide representation of a Macintosh
   file with CRC error checking.  Binhex 4.0 files are designed
   for communication of Mac files over long distance, possibly
   noisy, seven bit wide paths.

   [Difference from other binhex formats?]

   (1996-09-17)