Oracle database startup stages enterprise manager

Oracle database instance can be started in stages. This sequence can be viewed from Oracle Enterprise Manager Database Control. Here are the sequence of steps I've logged into OEM the Oracle Enterprise Manager as SYSMAN user with NORMAL Privilege (NORMAL in Drop-Down menu) 1) When database is in normal state (i.e) Open state with normal transaction operations 2) Shutdown the instance using SHUTDOWN IMMEDIATE command. This throws an error in OEM Database Control 3) Issue STARTUP command with NOMOUNT option. In Database Control Click OK.Instance status shows no mount 4) Mount the database by issuing ALTER DATABASE MOUNT; command. Click on refresh button at top right corner of database control and status changes to mounted 5) Open the database using ALTER DATABASE OPEN; command. This will show the status as open now