CURVE MANIPULATIONS
*******************

Smooth curves are achieved in QikDraw by selecting points lying on the 
curve and then applying piece-wise cubic curve fitting to the points.
BEZIER curves and B-SPLINES are also supported. A POLYLINE option
is available to group lines together.

For drawings with a large number of complex curves requiring a large
number of definition points, the program limit for points may be
exceeded. This can be overcome by "fixing" some of the curves through
the TRANSform option. "Fixed" curves will require a smaller number of
points for reference.

The following secondary selections are allowed:-

    ADD:-     Curves are added by selecting points (may or may not be 
              pre-defined).
              The graphical tertiary menu will be displayed. Three 
              options are allowed. If the OPEN UNCONTROLLED option is 
              selected, all points will be used to draw the open-ended 
              curve. If the OPEN CONTROLLED option is selected, curves 
              will be drawn from the second selected point to the 
              penultimate point. The first two points will define the 
              start tangent and the last two points will define the end 
              tangent. The curve will close itself if the CLOSE option 
              is selected.
    DELETE:-  Curves are deleted by locating a point lying on the curve.
              If option selected with the LEFT button, the user will be  
              able to delete curves in reverse order of storage.
    TRANS:-   Curves may be transformed into FIXED form to save storage
              and speed up display. This is the recommended way to 
              process a large number of complex curves. Fixed curved 
              cannot be modified, blanked or unpacked.
              Alternate selection allows for transformation of fixed
              curves back into the regular form.
    STYLE:-   Curves can have line styles as in lines.
    CHANGE:-  Curve specifications (pen, thickness, style) can be 
              altered to be those currently active by selecting this 
              option and then locating a point on the curve.
              Alternate selection allows for the change of:-
                a). CURVE TYPE, or
                b). PEN NUMBER only, or 
                c). Line style and thickness only. 
              This alternate selection also allows for changes in 
              GLOBAL mode.
    PEN:-     Specify pen number and line thickness as for lines.
    UNPAK:-   Unpacks the selected portion of the curve into line
              segments joining the definition points. The lines are
              created in the currently defined line style. The curve is
              retained. Useful in preparing for hatching of planes 
              (defining the connecting lines as construction line types).
    MERGE:-   Two curves may be merged. A new curve is generated. The new 
              curve takes the line style of the first curve selected.
    BREAK:-   A curve can be broken up into two by this option. The curves
              generated are of the regular form even if the original curve
              is fixed.
    BLANK:-   Blank out part of curve between two definition points.
              Alternate selection with the LEFT button allows for
              restoration of the blanked out portions.
    MODIFY:-  Adding curve definition points onto the curve.
              Alternate selection deletes curve definition points.
    