That clears up some confusion pgsalton and DanAdair, thanks.
What's been confusing to me was the little one-man "tube tent" bivy and the outer sleeping bag cover being called a bivy.
I can see where both would need to breath and breath well or else be wetter than being without. I'm thinking the bag cover would be useful in a single wall tent if one were stuck in some rainy weather and getting heavy condensation without a chance to dry out during the day.
I've also stuffed a down vest and at times a Kuiu Spindrift in my bag. That also makes it nice putting them on the next morning if it's frosty! And what I wear is similar to Dan, merino base layers and merino socks.
And by the way. I have a Gransfors Bruks Wildlife Hatchet. I bought it and thought I must be crazy paying what it cost. It is such a nice tool. I've never had buyer's remorse at all. Being a persnickety craftsman myself, I appreciate the craftsmanship, the sharp edge and it just feels great in the hand. I occasionally carry it on one or two day overnighters, just to play with. Absolutely don't need it but absolutely love it. I'll even walk around my campsite with it on my belt.
It just feels good.
