That indicates the user is a System Administrator I believe.

Edit: As noted by Nuno in the comments this has changed in SDL Web 8.5 with the introduction of the Privileges model.

See related question here: http://tridion.stackexchange.com/questions/16496/create-admin-user-in-sdl-web-8-5-via-core-service

That is Core Service but you will need to do something similar in your GUI extension.