IBM H SERIES RS/6000 - Manual (Page 88)

After you have entered and verified the password, the privileged-access password
icon flashes and changes to the locked position to indicate that your computer now
requires the password you just entered before running system programs.
Note: If you forget the power-on password, the battery must be removed for longer
than 30 seconds to reset the NVRAM. Contact your service representative for
assistance.
4-14 RS/6000 Enterprise Server Model H Series User's Guide