I woven upper yoke area, extending down the tops of the sleeves. The collar and placket are included in this, something I appreciate. I tend to dislike buttons on knits as they seem to pull at the buttons if you utilize any of the benefits of the stretch. The woven collar might also stand up a bit better then a knit one would, better protecting the neck.
In theory this design would add some weatherproofing and durability to the tops parts of the garment, the only thing I find odd is that the armpits are barely included in the woven section, perhaps one of the places where knit is the most desirable: