+ /*!
+ * A type for positions used in paragraphs.
+ * Each position is either occupied by a single character or an inset.
+ * For insets, the placeholder META_INSET is stored in the paragraph
+ * text, and the actual insets are maintained separately.
+ */
+ // FIXME: should be unsigned, but needs to be signed for a while to
+ // hold the special value -1 that is used somewhere
+ // Note that the signed property is also used in loops counting to zero.
+ typedef ptrdiff_t pos_type;