I am not sure on 10, but on 9 in the OrderRel table there are 2 fields "OurJobShippedQty" and "OurStockShippedQty", when I am writing queries/reports I always total these 2 field up to get the Release Shipped Qty (since we ship both form stock and from jobs) and then I compare that field to the OrderRel.OurReqQty field to determine is the line has shipped. However, I do not have a reason as to why Epicor would not be automatically closing those releases/lines as shipped when you are shipping those lines complete and marking the packing slip as such. We have not experienced this behavior, it always closes the release/line when we ship the release complete and mark the packing slip as shipped.
I believe (but could be wrong) that whenever you close a line thru the Menu (and not thru shipments) is marks the OrderDtl.VoidLine field as true (regardless if it shipped or not)