What do you mean by movement range?

Movement range is an anticipated range of thermal movement or seismic movement. For Example :- 1. A 100mm normal gap or installation gap is anticipated to have a range of horizontal movement of + 20mm or – 20mm could also be indicated as 100mm +/- 20mm, meaning the gap closes to minimum of 80mm and opens to a maximum of 120mm. 2. Seismic joints will typically have a movement range of 100mm +/- 50mm to +/-100mm.