HDV and AVCHD camcorders have Upper Field First.
The tricky part is when you confuse SD with DV. DV has Lower Field First. But not all SD is Lower Field First and can be Upper Field First.
So, at this time, I am not sure if Mercalli is grouping HDV and AVCHD under the "HDV Upper Field First" and considering "just Upper Field First" to be related to the non DV SD which has Upper Field First.
I am trying to research that now.
This is the closest that I came to a ProDad refinement of that video format setting in Mercalli.
For HDV (1440 x 1080), HDV Upper Field First is straight forward.
For DV, Lower Field First would is straight forward.
For SD (non DV), can be Upper Field First, so it would seem appropriate to use Upper Field First.
But, we know that AVCHD is Upper Field First, 1920 x 1080, and technically not HDV. But, the question pops up where to class AVCHD, under HDV Upper Field First or just Upper Field First ProDad Video Format choices. At this point, I would look at it under the HDV Upper Field First and leave Upper Field First for the SD (non DV).
But read the above link and what it seems to be saying about the use of the video format setting in Mercalli.
As per my experience with camera's, mostly all Hard disc based camera's are Upper Field first while Tape based camera's happen to be lower field first.