On a 1991 B-190 it is an A&E Horizon Case Awning.The manual is identified as "163011 A89 April 89"
These case awnings are fairly common. Just get the right length so that it fits on the B-Van superstructure and the awning support brackets that mount on the body of the van will clear doors and such.
These awnings roll into a case and use a handle to roll and unroll them. The rafter arms scissor out and the supports fold down from the outside edge of the awning so they can support the outside edge from the ground or by attaching to brackets on the van body.
This is not like the trailer awnings that roll up on a tensioned roller and have rafter arms that fold out from the trailer wall.
See A&E 11' 6" Horizon Case Awning - Camping World
or Case awning especially for recreational vehicle (US5044416)
to maybe get an idea.