When you perform any of the following tasks, you cause the system to register or re-register your interest in a data item and update your local cache vector to indicate that your locally cached copy of the data item is valid:

• Read a data item from the cache structure (REQUEST=READ_DATA).
• Write a data item to the cache structure (REQUEST=WRITE_DATA,WHENREG=NO).
• Read a data item from the cache structure for cast-out and request to register interest (REQUEST=CASTOUT_DATA,REGUSER=YES).