@var{collection}. If @var{require-match} is @code{nil}, the exit
commands work regardless of the input in the minibuffer.
+The user can exit with null input by typing @key{RET} with an empty
+minibuffer. Then @code{completing-read} returns @code{nil}. This is
+how the user requests whatever default the command uses for the value
+being read. The user can return using @key{RET} in this way regardless
+of the value of @var{require-match}.
+
The function @code{completing-read} works by calling
@code{read-minibuffer}. It uses @code{minibuffer-local-completion-map}
as the keymap if @var{require-match} is @code{nil}, and uses