For cache structures allocated in a coupling facility of CFLEVEL=4 or higher, you can issue a READ_DATA request with the RETURNDATA=NO keyword to suppress the read function so that no data is returned. Instead, the READ_DATA request will register interest in the entry without returning the associated data. Note however, that if the cache structure supports adjunct data and the data exists, the READ_DATA request will return the adjunct data in the area specified on the ADJAREA keyword. If you do not specify the ADJAREA keyword, the system does not return the adjunct data even if it exists. The CAAADJAREAVALID bit in the cache answer area indicates the presence of adjunct data in the area specified by ADJAREA.