 UNI                                                                Menu: SETOP
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 Unites two interpenetrating solid entities into a single new entity.

         1. (IND) first solid to unite
         2. (Y/N) confirm choice
         3. (IND) second solid to unite
         4. (Y/N) confirm choice
         5. (Y/N) keep the result?

 Description:
 This command unites two entities that interpenetrate.
 Parameters 1 and 2 ask you to identify the first entity and confirm your
 choice.
 Parameters 3 and 4 do the same for the second entity. The system displays the
 resultant entity and asks you (parameter 5) if you wish to keep it.
 The result of this process is a complex solid entity (data type 9). If only
 one of the entities involved in this operation is an axial wall the result is
 a complex wall that continues to possess wall characteristics but the commands
 \chaw, \chaa, \fixw, and \fixa no longer function.


         Example: \uni (ind) y (ind) y y

 Result: The two interpenetrating entities are fused into a single entity,
 which is saved.
 Limitations
 1. It is recommended to execute \uni on entities of the same color otherwise
    the color of the resultant entity is unpredictable.
 2. When two entities exist in different layers, the resulting solid will
    reside in the layer of the first entity.
 3. If \uni is executed on two entities that are not in contact with each other
    they will nevertheless be united into a single complex entity.
 4. The number of \uni commands that may be executed on any entity is limited
    by the maximum of 200 points on any one of its polygons. You will be
    notified if you go beyond this limit.
 5. It is not possible to execute \uni on negative entities.
 6. This command will not operate on placed entities that contain negative
    solids or 2D entities.
