Use of Fnd_log.STRING in PL/Sql code

Fnd_Log.STRING(log_level => Fnd_Log.LEVEL_STATEMENT,MODULE =>xxt.apps.custompackage name
                  ,message => 'your message');

FND: Debug Log Level   Codes

   LEVEL_UNEXPECTED     :  6
   LEVEL_ERROR          :  5
   LEVEL_EXCEPTION      :  4
   LEVEL_EVENT          :  3
   LEVEL_PROCEDURE      :  2
   LEVEL_STATEMENT      : 1
--------------------------------------------

FND: Debug Log Enabled : Yes

FND: Debug Log Module    Set this to %


Step 2
Login to the application and reproduce the problem.

Step 3
SELECT *
FROM fnd_log_messages
WHERE user_id = <id>
ORDER BY log_sequence DESC 




Why to set the profile option to statement level?
This profile option has following main levels.-
Error
Warning
Procedure
Statement

select * from fnd_log_messages where user_id = <id>and LOG_LEVEL =<log level>   



To purge data in production:

You can run concurrent program “Purge Debug Log and System Alerts”.


I have written a pl/sql concurrent process to interface Purchase Orders from 3rd Party System. How will add debug messages?
    fnd_log.STRING(log_level => fnd_log.level_statement
                  ,module    => '<module >'
                  ,message   => '<message >');

 Note:

fnd_log.string eventually calls procedure  FND_LOG.STRING_UNCHECKED_INTERNAL2. This procedure uses pragma AUTONOMOUS_TRANSACTION with a commit.