Olex2 Syntax
Selection: If one or more atoms are selected on the screen, then any command that acts on a selection will apply to the selected atoms only. If there is no selection, it will apply to all atoms. Instead of making a selection on the screen, a list of atom names can also be supplied. If a command has been successful, the selection will disappear. (Although there are a couple of exceptions to this rule)
Mode: If Olex2 is in a Mode, the chosen action will be applied to all subsequently clicked atoms. The mouse pointer will change from the default arrow symbol to signify that Olex2 is in a mode. To get out of a mode, simply press the Esc key.