V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

DTSS
       Dartmouth Time-Sharing System (OS)


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

DTSS

    The first commercial time-sharing system,
   created by Dartmouth College and sold by General Electric
   around 1967.

   GE's Information Service Divsion (ISD) marketed DTSS which was
   running on a system called GE-265 (a combination of the
   front-end processor the Datanet-30 and the GE-235).

   DTSS was ported (and significantly improved by GE ISD around
   1965-1966 on a combination of DN-30 and GE-635).  This
   proprietary system, called Mk-II, later improved by GE and
   renamed Mk-III, is still working today (1997) as part of the
   GE service bureau that also includes IBM and Unix
   computers.

   (1997-09-16)