Depending on the replacement policy of the cache, the tag entry might also contain one or more additional bits. For example, in a cache that implements LRU replacement, each tag entry must be able to record how many of the other lines in the set have been referenced since the last time that the line it corresponds to was referenced so that the replacement policy can locate the least recently used line when a replacement is required. This requires log2 (cache associativity) bits of data in each tag entry.