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## WYSIWYG-Principle

WYSIWIG (What you see is what you get) is known to all users of desktop publishing systems. Transferred to the CAD range this means that the user sees the expectable result before the command is finally terminated.
In SISCAD-P you have the WYSIWYG functionality available for all CAD commands. During the input of a CAD command the result valid at this moment is displayed. The position of the crosshair is used for the calculation of this first result. Any further input of parameters which modify geometry or cause the modification of parameters already put in is considered and the result is actualized correspondingly.
Example:

> A circular arc shall be drawn tangentially to two existing geometrical objects with given radii.

> The CAD command CREATE CIRCLE EER is suitable for this purpose.If you have created a circle and a straight line and want to draw a circular arc tangentially to them, you should select the above CAD command by clicking the corresponding icon. The system now expects you to identify the elements to which the tangential construction shall be made. The next step is the input of the desired radius. After this input the system can show you an advance result.

> The possible circular arcs are displayed on the graphic screen in a color especially reserved for this purpose (line partially broken).If several solutions are possible, you may select the desired one by simply clicking it.

> The modification of the already existing radius will be taken into consideration immediately. Not until the result on the screen meets your requirements you terminate the CAD command. The desired objects now are created with the desired display attributes. Undo operations thus become nearly superfluous.

With this example the basic principle should be made clear. This principle may be transferred to nearly all construction commands and thus can be understood very easily.

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