Exception
From Friend2Friend Wiki
If the F2F server detects an abnormal state, it throws soft exceptions, each of which has a unique code. These range from notices (0-2999), warnings (3000-4999), 'errors (5000-7999) to fatal (8000-9999). Codes of 8000 or over indicate an F2F server bug, so it throws a <f2f:fatal-error> and stops the system, otherwise the <f2f:exception> is added to the message that created it. If you can create these, please email the <f2f:fatal-error> back for diagnosis.
The available soft exceptions are documented in XHTML, or XML.
