startup open restrict

Not familar with this command before. Did a test as follows:

sys@TEST10G> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
sys@TEST10G> startup open restrict
ORACLE instance started.

Total System Global Area  612368384 bytes
Fixed Size                  1250428 bytes
Variable Size             163580804 bytes
Database Buffers          440401920 bytes
Redo Buffers                7135232 bytes
Database mounted.
Database opened.

sys@TEST10G> select logins from v$instance;

LOGINS
----------
RESTRICTED

sys@TEST10G> alter system disable restricted session;

System altered.

sys@TEST10G> select logins from v$instance;

LOGINS
----------
ALLOWED