@dfn{Self-documenting} means that at any time you can use special
commands, known as @dfn{help commands}, to find out what your options
-are, or to find out what what any command does, or to find all the
+are, or to find out what any command does, or to find all the
commands that pertain to a given topic. @xref{Help}.
@dfn{Customizable} means that you can easily alter the behavior of