[Rules] Edelweiss - Bunkers?

[HeyJude]

Hi everyone.  Sorry if this is posted in the wrong place.  I have a question about the OOB in Edelweiss Scenario 2: Arctic Frontier.  In the OOB the Soviets get 2 Bunkers, along with 10 entrenchments and can also have troops dug in.  Does anyone know what the rule for bunkers is?  I assume it must be different from entrenchments, otherwise why make them separate (unless they are just trying to keep the German poison gas attacks limited).  Are bunkers a holdover from an earlier version of the rules?  Or should I just treat them like entrenchments?  Any ideas are welcome.  Thanks everyone.