A tag entry contains the information necessary to record which line of data is stored in the line of the data cache that is associated with the entry. Each entry describes one cache line of data. As shown in Fig. 9-9, a tag entry consists of a tag field that contains the portion of the address of the line that is not used to select a set (the “remainder” field from Fig. 9-5), a valid bit that records whether or not the line associated with this tag array entry contains valid data, and a dirty bit (for write-