Bit of an odd error, unless I'm misreading it which is also likely. But Combat 4 in the PDF refers to an EDZ that doesn't exist on the provided maps. Its all ingress zones. I've assumed one of the ingress zones is meant to double up as the EDZ (or they all are EDZ/Ingress), as even the rules for the type of mission it is state there should be an EDZ even though I could see it being redundant for an experienced GM, but its not explained in the PDFs for either the Core Rules or Winter Scar.