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

software patent

    A patent intended to prevent others from using some
   programming technique.

   There have been several infamous patents for software
   techniques which most experienced programmers would consider
   fundamental or trivial, such as the idea of using
   exclusive-or to plot a cursor on a bitmap display.  The
   spread of software patents could stifle innovation and make
   programming much harder because programmers would have to
   worry about patents when designing or choosing algorithms.

   There are over ten thousand software patents in the US, and
   several thousand more are issued each year.  Each one may be
   owned by, or could be bought by, a grasping company whose
   lawyers carefully plan to attack people at their most
   vulnerable moments.  Of course, they couch the threat as a
   "reasonable offer" to save you miserable years in court.
   "Divide and conquer" is the watchword: pursue one group at a
   time, while advising the rest of us to relax because we are in
   no danger today.

   Compuserve developed the GIF format for graphical images
   many years ago, not knowing about Unisys's 1985 patent
   covering the LZW data compression algorithm used in GIF.
   GIF was subsequently adopted widely on the Internet.  In
   1994 Unisys threatened to sue Compuserve, forcing them to
   impose a sublicensing agreement for GIF on their users.
   Compuserve users can accept this agreement now, or face Unisys
   later on their own.  The rest of us don't have a choice -- we
   get to face Unisys when they decide it's our turn.  So much
   trouble from just one software patent.

   Patents in the UK can't describe algorithms or mathematical
   methods.

   See also LPF, software law.

   patent search
   (http://sunsite.unc.edu/patents/intropat.html).

   (1995-01-06)