References:
https://docs.oracle.com/cd/E17559_01/em.111/e16599/appdx_creating_db_templates.htm# CJACEDCD

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:
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SQL> ALTER TABLE Tab_tst1 DROP PARTITIONS
Tab_tst1_PART5, Tab_tst1_PART6, Tab_tst1_PART7;
Table altered
SQL>
Restrictions :
-You can't drop all partitions of the table.
-If the table has a single partition, you will get the error: ORA-14083: cannot drop the only partition of a partitioned.

A single extent can never span data files.
https://docs.oracle.com/database/121/CNCPT/logical.htm#CNCPT1095

Explanation/Reference:
Explanation:
https://docs.oracle.com/database/121/CNCPT/process.htm