$modelgainQWregion is a command to assign the quantum well region number in cavity mesh and gain mesh. The format is
$modelgainQWregion
N cavQWlayer(1) ... cavQWlayer(N) gainQWlayer(1) ... gainQWlayer(N)
For example:
$modelgainQWregion
3 6 8 10 6 8 10