the middle one
a mirror image of the one in the character Dog.
The four around parts are grass. A dog is running on the grassland, which means Vast.
The character Vast is similar to character Sunset (Post 196)
The surrounding is same, 4 grass. The middle is character Sun.
The small seal script for character Vast is
the middle one
is the character Dog, surrounded by grass.
The clerical script for the character Vast is
The middle one
is character Dog, the grass on the top is a little bit different from the grass on the bottom, but there are all grass.
The current standard printing script (song script) is
莽
Its pinyin is Mang3.