polygon-union-delete-originals

See this command in the command table.

To access this command:

Digitize ribbon >> Tools >> Combine >> Polygon Union Unique.
Using the command line, enter "polygon-union-delete-originals".
Display the Find Command screen, locate polygon-union-delete-originals and click Run.

Command Overview

Create a unified perimeter based on other loaded closed strings. How this command operates depends on the relative arrangement of the target strings, erasing the original string data.

If overlapping polygons are selected in any 3D window, this command creates a new polygon which contains the area inside all of them.
If separate polygons are selected in any 3D window, this command creates an identical polygon for each selected item.

Note: A variation of this command - polygon-union ("plyu") - retains the original polygon string data.