Oracle spfile default location

Hi,

I was told in Linux, the Oracle spfile default location is located at $ORACLE_HOME/dbs ,

I have a database with spfile in ASM

SQL> show parameter spfile

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

spfile                               string      +DATA/DBTEST2/PARAMETERFILE/spfile.300.990280177

and there is no initdbtest2.ora in the dbs ,

when I start the database with sqlplus, the database somehow know the spfile location in ASM,

is there any others configuration file control this?

SQL> startup

ORACLE instance started.

Total System Global Area 8589934592 bytes

Fixed Size                  8641256 bytes

Variable Size            1543505176 bytes

Database Buffers         7012876288 bytes

Redo Buffers               24911872 bytes

Database mounted.

Database opened.