Explanation
RMAN> select name,open_mode from v$pdbs;
using target database control file instead of recovery catalogNAME OPEN_MODE----------
----PDB$SEED READ ONLYORA12P1 READ WRITEORA12P2 MOUNTED
RMAN> backup tablespace ora12p2:users;
Starting backup at 31-MAR-14allocated channel: ORA_DISK_1channel ORA_DISK_1: SID=137 device type=DISKchannel ORA_DISK_1: starting full datafile backup setchannel ORA_DISK_1: specifying datafile(s) in backup setinput datafile file number=00013 name=/appl/oradata/cdbroot/ORA12C1/F5D05369C4B23E83E0430100007F6D99/datafile/o1_mf_users_9mhr0 ORA_DISK_1: starting piece 1 at 31-MAR-14channel ORA_DISK_1: finished piece 1 at 31-MAR-14piece handle=/appl/oradata/flash_recovery/ORA12C1/F5D05369C4B23E83E0430100007F6D99/backupset/2014_03_ tag=TAG20140331T001832 comment=NONEchannel ORA_DISK_1: backup set complete, elapsed time:
00:00:01Finished backup at 31-MAR-14
Starting Control File and SPFILE Autobackup at 31-MAR-14piece
handle=/appl/oradata/flash_recovery/ORA12C1/autobackup/2014_03_31/o1_mf_s_843610715_9mhzdcv8_.bkp comment=NONEFinished Control File and SPFILE Autobackup at 31-MAR-14 RMAN> The above example illustrates that if root container is open and in archivelog it can do the backup of tablespace whether the pdb is mounted or open.

Explanation
Multipartition maintenance enables adding, dropping, truncate, merge, split operations on multiple partitions.
A: Merge Multiple Partitions:
The new "ALTER TABLE ... MERGE PARTITIONS " help merge multiple partitions or subpartitions with a single statement. When merging multiple partitions, local and global index operations and semantics for inheritance of unspecified physical attributes are the same for merging two partitions.
B: Drop Multiple Partitions:
The new "ALTER TABLE ... DROP PARTITIONS " help drop multiple partitions or subpartitions with a single statement.
Example:
view plaincopy to clipboardprint?
SQL> ALTER TABLE Tab_tst1 DROP PARTITIONS
Tab_tst1_PART5, Tab_tst1_PART6, Tab_tst1_PART7;
Table altered
SQL>
Restrictions:

Explanation
http://docs.oracle.com/database/121/BRADV/flashdb.htm#BRADV529http://docs.oracle.com/database/121/BRA

To perform operations on a single PDB, you can connect as target either to the root or directly to the PDB.
*(A)If you connect to the root, you must use the PLUGGABLE DATABASE syntax in your RMAN commands. For example, to back up a PDB, you use the BACKUP PLUGGABLE DATABASE command.
*(C)If instead you connect directly to a PDB, you can use the same commands that you would use when connecting to a non-CDB. For example, to back up a PDB, you would use the BACKUP DATABASE command.
Reference:Oracle Database Backup and Recovery User's Guide12c,About Backup and Recovery of CDBs