[Rules] Can non-personnel units dig in?

[John_S1973]

I am a newbie to PG and really like the game!   I was not sure if digging-in was limited solely to personnel units and leaders or if weapon units (AT guns, APC's, Tanks, other vehicles) can dig in.  It wasn't that unusual for these weapons to be dug in in WW2, particularly on the steppe or desert due to lack of defensive terrain.  Thoughts?

Thanks all for your help!