Now, there is a further variant on the Clark CLEAN that is used by MX\ (Schwab 1984). During the major cycle, the Fourier transformed CLEAN components are subtracted from the ungridded residual u,v) data, instead of the residual gridded u,v) data (i.e., the FFT of the residual image). This means that the subtraction is more accurate, and allows CLEANing of virtually the whole image, instead of just the inner quarter.