+ doc: /* *Non-nil means when reading a filename start with default dir in minibuffer.
+If the initial minibuffer contents are non-empty, you can usually
+request a default filename by typing RETURN without editing. For some
+commands, exiting with an empty minibuffer has a special meaning,
+such as making the current buffer visit no file in the case of
+`set-visited-file-name'.
+If this variable is non-nil, the minibuffer contents are always
+initially non-empty and typing RETURN without editing will fetch the
+default name, if one is provided. Note however that this default name
+is not necessarily the name originally inserted in the minibuffer, if
+that is just the default directory.
+If this variable is nil, the minibuffer often starts out empty. In
+that case you may have to explicitly fetch the next history element to
+request the default name. */);