In addition to the information needed for the sections with a constant channel depth a second channel depth must be entered with the compression and decompression section. If for the channel depth h_1 a greater value is entered into the input mask of the compression section than for the beginning channel width h_0 REX/PSI will change this section automatically into a decompression section. This is also valid vice versa.

Another special feature is that a constant pitch does not have to be used, but can be specified separately for the start and end of the zone. A continuous change in the aisle gradient is calculated over the entire length of the zone.