CIRCLE/ARC MANIPULATIONS
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Circles/arcs may be generated by various options. If ARC manipula-
tions are to be specified, the ARC option must be selected before
selecting another secondary option (e.g. CIRCLE ARC OPT).

The following secondary selections are allowed:-

    OPT:-     POLYGON allows users to specify regular incribed or 
                      circumscribing polygons.
              SEGMENT allows users to insert additional points onto arcs
                      or circles with or without connecting lines.
    ADD:-     Circles/arcs are added according to the option selected.
              The graphical tertiary menu will be displayed. Many 
              options are allowed. These are:-
                  CIRCLES                    ARCS
              Centre Pt + Rad (Default)   Centre Pt + Angle (Default)
              Centre Pt + Pt              2 Pts + Radius
              2 Pts as Diameter           3 Pts
              3 Pts                       Centre + Tangent line + Ang
              2 Pts + Radius              Tangent point to Pt
              Centre + Tangent line       Tangent pt + Rad + Ang
              Tangent Pt + Radius         Tangent pt + Tangent line
              Tangent Pt + Tangent        2 Tangent lines + Radius
              2 Tangent lines + Radius    Semi-circle from 2 Pts
              3 Tangent lines             2 Pts and Centre
              
              With some of these options, an indicator point would be 
              required for the program to decide on the circle/arc 
              orientation.
           
              If the Circles to 3 Tangent Lines Option is selected with
              the LEFT BUTTON, QikDraw will allow the user to
              insert circles tangent to any combination of 3 entities
              including Lines, Circles, and Points.

    DELETE:-  Circles/arcs are deleted by locating the cursor near to
              the circumference of the circle/arc.
              If option selected with the LEFT button, the user will be  
              able to delete circles in reverse order of storage.
    TRANS:-   Transforms the CIRCLE/ARC into POINTS, LINES and PLANES.
              Useful in generating regular polygons.
              Or else transform Circle into Arc or vice versa. The Arc
              is always defined anti-clockwise. A full circle is formed
              if the start and end points of the arc is the same.
    STYLE:-   Circles/Arcs can have line styles as with lines.
    CHANGE:-  Circle/Arc specifications (pen, thickness, style,side)
              can be altered to be those currently active by 
              selecting this option and then locating the arc.
              Alternate selection allows for the change of PEN NUMBER
              only, or line style and thickness only. This selection
              also allows for changes in GLOBAL mode.
    PEN:-     Specify pen number and line thickness as for lines.
    SIDE:-    Circles/Arcs are defined as a number (default 32) of
              straight line segments. This number may be redefined by 
              the user to, say, define regular polygons.
    BREAK:-   Break up circles/arcs/ellipses into segments. Points to
              define the extremities of the segments must lie on the 
              circle. 
              Alternate selection allows for blanking out of part of
              a circle/arc/ellipse. Location points does not have to
              lie on the circle. Intersections will be generated.
    ELLIP:-   Ellipses can be generated by defining the centre and a
              point on the major axis, or by defining the major axis.
              After generation, ellipses are treated just like circles.
              Elliptical arcs can be generated by modifying the full
              ellipse.
    CEN-L:-   This option allows a pair of lines to be automatically
              generated at the centre of circle/arc.
