open TELEMAC-MASCARET The mathematically superior suite of solvers

I am working on a wave simulation using TELEMAC-ARTEMIS, and I would like to add a sponge layer near the open boundaries to absorb outgoing waves and minimize reflections.

I found the DISSIPATION keyword in the steering file (.cas), but I am unsure how to correctly define the dissipation region. Specifically, I have a rectangular domain and want to apply the sponge layer near all four boundaries.