- /* Following child (to right or down) at same level of tree */
- Lisp_Object next;
- /* Preceding child (to left or up) at same level of tree */
- Lisp_Object prev;
- /* First child of this window. */
- /* vchild is used if this is a vertical combination,
- hchild if this is a horizontal combination. */
+
+ /* Following (to right or down) and preceding (to left or up) child
+ at same level of tree. */
+ Lisp_Object next, prev;
+
+ /* First child of this window: vchild is used if this is a vertical
+ combination, hchild if this is a horizontal combination. Of the
+ fields vchild, hchild and buffer, one and only one is non-nil
+ unless the window is dead. */