SQL & PL/SQL

The oracle documentation states that

"Oracle does not support global nonprefixed partitioned indexes"

I could able to create the global partition index on this table.. Here is the small test case

SQL> create table t ( x int, y int, z int )

  2  partition by range(x)

  3  (partition p1 values less than (1),

  4  partition p2 values less than (2),

  5  partition p3 values less than (3)

  6  );

Table created.

SQL>

SQL>

SQL> create index idx_t on t(y) global;

Index created.

Please help me to understand the concept in a better manner.