* Because tablespaces in different PDBs can have the same name, to eliminate ambiguity you must connect directly to a PDB to back up one or more of its tablespaces.
* To back up tablespaces or data files:
Start RMAN and connect to a target database and a recovery catalog (if used).
If the database instance is not started, then either mount or open the database.
Run the BACKUP TABLESPACE command or BACKUP DATAFILE command at the RMAN prompt.

Explanation/Reference:
Explanation:
http://docs.oracle.com/database/121/ADMIN/cdb_pdb_admin.htm#ADMIN14017

Explanation/Reference:
Explanation:
If you run multiple AUDIT statements on the same unified audit policy but specify different EXCEPT users, then Oracle Database uses the last exception user list, not any of the users from the preceding lists. This means the effect of the earlier AUDIT POLICY ... EXCEPT statements are overridden by the latest AUDIT POLICY ... EXCEPT statement.
Note:
* The ORA_DATABASE_PARAMETER policy audits commonly used Oracle Database parameter settings.
By default, this policy is not enabled.
* You can use the keyword ALL to audit all actions. The following example shows how to audit all actions on the HR.EMPLOYEES table, except actions by user pmulligan.
Example Auditing All Actions on a Table
CREATE AUDIT POLICY all_actions_on_hr_emp_pol
ACTIONS ALL ON HR.EMPLOYEES;
AUDIT POLICY all_actions_on_hr_emp_pol EXCEPT pmulligan;

Explanation
Transportable tablespaces were introduced in Oracle 8i to allow whole tablespaces to be copied between databases in the time it takes to copy the datafiles. It is supported in Oracle 11g.

* The CREATE DATABASE ... ENABLE PLUGGABLE DATABASE SQL statement creates a new CDB. If you do not specify the ENABLE PLUGGABLE DATABASE clause, then the newly created database is a non-CDB and can never contain PDBs.
Along with the root (CDB$ROOT), Oracle Database automatically creates a seed PDB (PDB$SEED). The following graphic shows a newly created CDB: * Creating a PDB Rather than constructing the data dictionary tables that define an empty PDB from scratch, and then populating its Obj$ and Dependency$ tables, the empty PDB is created when the CDB is created. (Here, we use empty to mean containing no customer-created artifacts.) It is referred to as the seed PDB and has the name PDB$Seed. Every CDB non-negotiably contains a seed PDB; it is non-negotiably always open in read-only mode. This has no conceptual significance; rather, it is just an optimization device. The create PDB operation is implemented as a special case of the clone PDB operation.