And just to complete the full set of 'linear cover' I'd better include
WALLS too
Walls give an exposure rating reduction to all infantry-class units and guns
within 15 metres of it (30% compared to 75% in open)
Walls give
hulldown to tanks within 15m
Note - with all the units, the 15m shrinks dramatically if firer is higher or is firing at sharp angle across wall, so always get as close up to it as possible but NOT actually ON the wall or their exposure skyrockets to 95% (think "sitting ducks")
Static non-firing infantry and guns in the 15m zone are harder to spot than if they were in the open (approaching enemy infantry will spot inf and gun units in the 15m zone when they close to about 280m, compared to 880m in the open)
But infantry units and guns on 'Hide' in the 15m zone will not be spotted until approaching infantry is about 20 m away.
However the 20m does not apply if the enemy saw them before they went on hide,in which case the usual 280m spotting figure applies instead.
Hiders DO have LOS over wall, they're not blind.
Halftracks, wheeled vehs and guns
can't cross walls
TACTICAL SUMMARY -
1 - Get your units (inc tanks) within the
15-metre protection zone behind walls, the closer to the wall the better
2 - If you don't plan on shooting for a while, put your inf and guns on Hide in the zone so the enemy won't see them until they close to a pointblank 20m