- * and functions \var{ascend_filter} and \var{descend_filter} from
- * \var{WRegion}s (\var{to}, \var{from}), used to decide when to descend
- * or ascend into another region. (TODO: more detailed explanation.)
+ * and boolean functions \var{ascend_filter} and \var{descend_filter}
+ * on \var{WRegion} pairs (\var{to}, \var{from}), are used to decide when
+ * to descend or ascend into another region.