hi, folks when I conduct clipping an image via an vector EVF file, I found some guy employed procedure 'ENVI_MASK_DOIT' to create a mask for the image file. But I can not find any information about this procedure in ENVI / IDL help. what I can make sure is that this is not an user defined procedure. I want to know the detail information of this procedure, ps: the code is : ==================== ENVI_MASK_DOIT,$ AND_OR =1, $ /IN_MEMORY, $ ROI_IDS= roi_ids, $ ns = ns, nl = nl, $ /inside, $ r_fid = m_fid out_dims = [-1,xMin,xMax,yMin,yMax] ======================= thanks.