SKETCHER enables the user to draw a compound to specify all the information required by LIBCHECK to generate an complete structure description. SKETCHER can also invoke REFMAC5 to generate an idealized structure. (a) shows a finished basically two-dimensional sketch before running LIBCHECK and (b) shows the resultant structure idealized with REFMAC5. To create the sketch, the user can choose from the tool panel on the left to add a single atom or ring structure or to delete atoms or bonds. Appropriate mouse clicks in the main viewing window will select the active atom to which new fragments are bonded and place the new fragment or edit the bond type. New atoms are always initially carbon, but the element type and atom name can be edited in the table in the top right of the window. The atom chirality is listed and can be edited in the table in the bottom right of the window.