In my oracle V9R2, I temp file got deleted from O/S level. But I startup my database successfully.

SQL> startup
ORACLE instance started.

Total System Global Area 135338868 bytes
Fixed Size 453492 bytes
Variable Size 109051904 bytes
Database Buffers 25165824 bytes
Redo Buffers 667648 bytes
Database mounted.
Database opened.

And when I am querying v$tempfile it is showing the details, but when I am querying dba_temp_files , I am getting the expected following error

ERROR at line 1:
ORA-01157: cannot identify/lock data file 201 - see DBWR trace file
ORA-01110: data file 201: 'E:\ORACLE\ORA92\BUCHKU\TEMP01.DBF'

But I wonder how Oracle allows me to startup my database successfully. Can anybody give me some details on this? I will appreciate.