ssl_engine_log format, tracing sessions

Is there a good reference for the format of the ssl_engine_log?  I am trying to trace a session from start to finish and I am finding it near impossible when there is more than one session active.  When a session starts, I see somthing like this:

[22/May/2003 15:31:57 08555] [info]  Connection to child 4 established (server foo.bar.com:443, client 10.10.10.10)

Can someone tell me what the "08555" means?  It does not identify this session alone, or at least it does not appear to.  Is it possible to trace one session from the logs?

Thanks for any help that can be provided.