- VALUE_TYPE_EVAL = 4, // Evaluation cache
- VALUE_TYPE_EV_UP = 5, // Evaluation cache for upper bound
- VALUE_TYPE_EV_LO = 6 // Evaluation cache for lower bound
+ VALUE_TYPE_EVAL = 4, // Static evaluation value
+ VALUE_TYPE_NULL = 8, // Null search value
+
+ VALUE_TYPE_EV_UP = VALUE_TYPE_EVAL | VALUE_TYPE_UPPER,
+ VALUE_TYPE_EV_LO = VALUE_TYPE_EVAL | VALUE_TYPE_LOWER,
+ VALUE_TYPE_NS_LO = VALUE_TYPE_NULL | VALUE_TYPE_LOWER,