By "former berm" I mean the protective walls built up to 1987, with the exception of smaller extensions (e.g. at Guerguerat 2021), in the gradual pushback of the areas under Polisario/separatist influence by the Royal Moroccan Armed Forces.  See the overview of the walls in:  https://en.wikipedia.org/wiki/Moroccan_Western_Sahara_Wall#/media/File:Western_sahara_walls_moroccan_map-en.svg  in: https://en.wikipedia.org/wiki/Moroccan_Western_Sahara_Wall
If you zoom in, you will see the parts of the historic walls already marked on Open Street Map! Best regards  Tilges