[DRG]

The fortifications and bunkers that were given a 1xx carry capacity were done that way so a player could "load" units, including mortars and any other crew served gun, into the armed bunker for protection. Theoretically, you could "load" mortars and their crews into a bunker/fort that has a 1xx carry capacity and "unload" them during the game, fire some mortar rounds then scoot back into the bunker for protection from enemy return fire fire.

IDK if anyone has actually done that but it could be done. The 1xx means you could hide an AT gun in there as well

As for shelter bunkers in scenarios, there are DOZENS of them in the scenarios.

From the SQL tab in ScenHack run

select distinct ScenNum, sTitle, Unit, uName , uclass from sData where (( LOWER(uName) like "%shelter bunker%"))
and uClass=0

"Theoretically" caves or concrete bunkers with a 2xx carry cap could be built to hide vehicles in. There are none built in the game but they could be built by a scenario designer using the in-game editor to, among other things simulate a Railroad tunnel.