What ar those Dynare-Generated Variables for?

iy_
ykmin_
ykmax_
xkmin_
xkmax_
zkmin_
zkmax_
I found them in the xxx.m file generated by Dynare, but I don't know what the functions of them are.
ykmin_
ykmax_
xkmin_
xkmax_
zkmin_
zkmax_
I found them in the xxx.m file generated by Dynare, but I don't know what the functions of them are.