R12: Aware about context file changes !!

Here is the main change in R12. Context File is no more in $APPL_TOP/admin directory!!!
Appltop context file has been moved to $INST_TOP/appl/admin directory.
Experienced Apps DBA's usually changes context files manually rather changing by OAM.Oralce Strongly suggest to use OAM to modify the context file.
I worked recently with 11i to R12 upgraded environment, where actual context file was present in $INST_TOP/appl/admin and old copy was present in $APPL_TOP/admin, one of my 11i experienced colleague modified $APPL_TOP/admin context_file and ran autoconfig accidentally which made big mess.
It led to rework and another downtime in Alpha environment.
11i Apps DBA's who are moving to R12 have to remember this. Irrespective of 11i or R12, I would suggest to use 'vi $CONTEXT_FILE' after making the copy of the context file by 'cp $CONTEXT_FILE_bkp_date'. Otherwise use OAM!!
you can get the context_file paths from FND_OAM_CONTEXT_FILES

Name Null? Type
===================================================
NAME
VERSION
PATH
LAST_SYNCHRONIZED
TEXT
LAST_UPDATE_DATE
LAST_UPDATED_BY
CREATION_DATE
CREATED_BY
LAST_UPDATE_LOGIN
NODE_NAME
STATUS
SERIAL_NUMBER
EDIT_COMMENTS
CTX_TYPE