Radars, antennas, surveillance both manned and unmanned observation posts, command and control centres, man portable radar systems (Anti mortar/artillery, strike guidance systems), ECM/jamming, tracked recovery vehicles, mine clearing equipment, pontoons/bridge layers and trench digging equipment.
I believe it refers mostly to engineering equipment (mobile bridges, mine clearing vehicles, etc) and as a catch-all for random things that don't fit into the other categories.