What is oradiag_oracle directory in /home/oracle in 11.2?

This directory is created in the home directory of the oracle user, after making a local connection.

I had tested it as follows:

[oracle@geoppdb01]:/home/oracle> ls -ltr
total 16
-rw-r--r-- 1 oracle oinstall 15621 Jan  5 11:51 db.rsp
[oracle@geoppdb01]:/home/oracle> date
Thu Feb  4 19:52:12 EET 2010

--- made a local sqlplus connection after then

[oracle@geoppdb01]:/u01/app/oracle/product/11.2.0/dbhome_1> sqlplus / as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Thu Feb 4 19:52:22 2010

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> !date
Thu Feb  4 19:52:26 EET 2010

-- check the folder, here it comes to life:)

[oracle@geoppdb01]:/home/oracle> ls -ltr
total 20
-rw-r--r-- 1 oracle oinstall 15621 Jan  5 11:51 db.rsp
drwxr-xr-x 3 oracle oinstall  4096 Feb  4 19:52 oradiag_oracle
[oracle@geoppdb01]:/home/oracle>