When the Starfleet Corps of Engineers was first mentioned in TWoK I assumed they were a 'public works'/combat engineer-type organisation similar to the US Army Corps of Engineers or the Seebees, and the fleet engineers like Scotty, LaForge etc would be under Starfleet Operations (Engineering Operations was mentioned at least once on viewscreens, there also seems to be a Starfleet Engineering (Group/Division/Corps) under Starfleet Research and Development (the ASDB may be part of this)), on the other hand, TrekLit seems to suggests that all Starfleet engineers are part of the SCE (making it more like the British Army REME), which doesn't really make sense to me given the original canon reference?