Choice of reading frame is provided, In survey mode all three reading frames are tried, and a report of the maximal peptide length is given. The complementary nucleic acid strand may be investigated as well. The symmetry operations of the appropriate space group may be applied to give the structure of a single unit cell, or alternatively a nest of cells may be formed. A comprehensive editing facility is present which allows the cleavage planes of the crystal to be exposed. However, it has been designed to be easy to use.
Control is achieved by use of very explicit pop-up menus.
These guide the user to those operations which are permissible at each stage. Structure manipulation and some other features are controlled by the use of cursor picking on static menus, and in some cases the functions of these menus is duplicated by the function keys. The program is designed to run on current Silicon Graphics workstations but will work on many of the older models. The current version of the program is designed to use version 6.5.x of the IRIX operating system, but will work on earlier versions . For convenience the system is shipped with executable versions of programs for versions 6.5 of the IRIX system in addition to full source of all the programs.