Much like the select= for visibility data, this selects a portion from your miriad image data cube for further processing. Again, details are in the Users Guide,we merely provide this in brief form here. The mirhelp region command also provides more details.
images(z1,z2) quarter(z1,z2) boxes(xmin,ymin,xmax,ymax)(z1,z2) polygon(x0,y0,x1,y1,x2,y2,...)(z1,z2) mask(file) abspixel relpixel relcenter arcsec kms