It displays a protractor in any one of three planes (X-Y, Y-Z, Z-X).

When starting this command, the command which was starting before it is automatically ended.
A procedure is shown below.
1. It starts [Protractor] command.
2. It drags the left button of the mouse on three planes (X-Y, Y-Z, Z-X) and it displays a circle.
A protractor (scale : 5 degree) is displayed in the circle position when ending a drag.
This command doesn’t end automatically. As for the way of ending, refer to The way of command’s ending. When
ending a one’s own command, a protractor is erased. However, when ended by the other command, a protractor isn’t erased.
When erasing a protractor, it starts [Protractor] command once again.