15.64.59.13  Revisions   - Originally  there  was  a  major  problem  with
TOPDRAWER.  The documented definition of THETA was not  the  same  as  the
actual  definition.   THETA  was  actually  measured  from  the Y axis and
positive valued put the eye closer to the positive  X  axis.   The  actual
definition  has  been  modified  to  conform to both the documentation and
conventional notation.  If this is a problem, you may return  to  the  old
definition by:
     SET REVISION=1.