Where there is a finite set of meaningful text inputs (symbol names, names of existing files or editor commands, and so on) the IDE helps you to enter your text by offering completion . When you invoke completion, the system takes your partial input and either:
When your input remains partial, you may repeat the completion gesture.
When you see a choice of the possible meaningful inputs, certain gestures allow you to narrow the choice and quickly select the desired input, as described in Selecting the completed input.
LispWorks IDE User Guide (Unix version) - 25 Nov 2011