[cctbxbb] cropping out a fragment

Hi all, I'd like to crop out a portion of a fragment (say a helix) from real_map by specifying fractional coordinates. would be nice to know if there is any specific routine for this. (oh .. & ++ option like crop only 2 angstroms from the location of the atom would be really nice). thankx Best, Mona ~.~.~.~><~.~~.~.~. Institute of Biochemistry, Institut of Neuro- and Bioinformatics Graduate School for Computing in Medicine and Life Sciences University of Lübeck, Ratzeburger Allee 160 Lübeck 23538 Germany