Una- funny you ask that now. Just pulled the mysterious one out of the closet for closer inspection. It is summer here, so it will likely be at least a month before a cool enough temperature comes along.
I tried something different with it today. I don't think I've seen anyone here try it, but with all the posts, I could have easily missed it. Apologies if this is redundant.
The first time I snapped the top snap, I pulled it across to the far snap, creating a high neck that induced fears of choking and not much flattery here. I didn't see that there were two high snaps on the very top of what becomes the collar when left open or top undone. I tried those two top snaps together, which created a low funnel shaped neckline that protruded stiffly straight out about 9 inches from my shoulders. I left the bottom snap undone. While some may like it this way, I found the protrusion cumbersome until I folded the center over the snaps, allowing about an inch and a half of the ribbed fabric interior to show. Love it. Nice open neck look and for those who find the super lapels overwhelming, this may change everything. If there were an additional snap in the center of the center, it would close appropriately this way, avoiding the pulling I am finding with the current asymmetrical snap location. Apart from that one center snap, the fit of this is perfect, so I didn't want to size up. Now I can wear it top snapped or open. I'll see if it is worthwhile to add that extra snap.
A workhorse is born. Big thanks to all for posting this item; it is both fun and a true bargain.