change with keep and nokeep

RMAN> change backupset 192 keep until time 'sysdate+20';

using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
using channel ORA_DISK_4
using channel ORA_DISK_5
keep attributes for the backup are changed
backup will be obsolete on date 07-JUN-14
backup set key=192 RECID=192 STAMP=847802445



RMAN> change backupset 192 nokeep;

using channel ORA_DISK_1
using channel ORA_DISK_2
using channel ORA_DISK_3
using channel ORA_DISK_4
using channel ORA_DISK_5
keep attributes for the backup are deleted
backup set key=192 RECID=192 STAMP=847802445