MSW Motor Technics MSW-CC-450-130 Manuel D'utilisation page 13

There are zippers on the corner of the cover - they enable access to each of the
walls of the trailer without the necessity of taking off the entire cover.
Special straps on the side walls (to be pulled under the bottom of the trailer) serve
to secure the cover and prevent it from being blown away by the wind.
3.2.
Preparation
BEFORE PUTTING ON THE COVER: