- * "start_display_move_num" is the (half-)move number to start displaying the PV at.
- * "score" is also evaluated at this point.
+ * "start_display_move_num" is the (half-)move number to start displaying the PV at,
+ * i.e., the index into pv.
+ *
+ * "score" is also evaluated at this point. scores can be empty and is frequently
+ * sparse; it's generally only really useful for history (we obviously don't know
+ * much about how the score will * move during e.g. a PV, except that a mate/TB
+ * counter might go down).