Main Help → All Commands → MPM Grid and Material Points → TartanAOI
The commands defines one or more areas of interest (AOI) when using a Tartan grid:
TartanAOI x1,x2,nx,y1,y2,ny
where
Besides defining AOI's, a Tartan grid needs to use GridHoriz (and maybe GridVert andGridDepth too) to define how cells change size outside of AOIs. Full details on creating Tartan grids are on the OSUPdocs wiki.