OpenTransport

from The Free On-line Dictionary of Computing (8 July 2008)

OpenTransport
OT

   <networking> (OT) A complete reimplementation of all levels of
   the {Macintosh} {networking} code including "Classic"
   {AppleTalk} and {MacTCP}.  It appeared in {MacOS} revision
   7.5.3 [or earlier?  Date?].

   (2000-08-13)