Patterns for pid and level

[Danny Pike]

I want to be able to put the process ID in my debug output, as well as 
single-character versions of the levels (w, e, d etc instead of "WARN", 
"ERROR", "DEBUG").

I have already modified my version of log4cxx to support these but it would 
make me more comfortable if they could be added to the standard build. In 
particular, what is the system (if any) that people are using to choose the 
pattern token in the format string (%F, %L etc). The only comment in the 
source that I can find appears to be incomplete. Is there a standard way of 
deciding what these should be?

I'm happy to make the code changes myself (as I've already done it on my 
own copy), but they are scattered over several files in the source so it's 
not just a case of uploading one or two whole files.

Regards,
DP