Altering Planes

If you wish to change which side of a plane is retained or discarded, you can do this by reversing the plane’s orientation if it is an FPLA and by changing the DIR or reordering the WPOS points for a SPLA. The CHANGE ACTION command, for example:

will do this for you by altering either the DIR or NORM attributes depending on the plane type. A PPLA cannot have its action reversed since it does not have an orientation.

Of course, changing the PMOD of the appropriate VSEC element would have the same apparent effect as a CHANGE ACTION operation in this case, but whereas the former operation only changes the view section representation, the latter operation changes the Plane database element itself.

The CHANGE ACTION command is valid at any Plane element, and at WPOS element level in the case of a Stepped Plane.

If you require a plane point to be moved, that means, either a POS attribute for a PPLA or an FPLA, and the POS attribute of a WPOS element for an SPLA, the BY command can be used. For example:

For an SPLA, the BY command will move the complete plane, that means, the POS attribute will be changed for all of the SPLA’s member WPOS elements.

You can delete individual WPOS elements in the normal way but you can also delete several at once using the command:

DELETE STEP number number

where the number arguments define the list position range of the points to be deleted.