[syslog-ng]using flags in log statements

[nate]

how would I set a flag, such as "final" in a log statement?

I read on this sample config that it can be done but I don't
see any examples:

http://www.campin.net/syslog-ng/expanded-syslog-ng.conf

I tried just putting final; and that didn't work and tried
flag(final); that didn't work either.

for some reason the mime setup seems to be broken on
www.balabit.com when I try to access the documentation
it sends me the file with type application/octet-stream
which phoenix then prompts to download, I can save it to
disk and view it but it's only the table of contents..

not sure if the online docs talk about it or not, the manpage
for syslog-ng.conf does not mention flags(freebsd 4.8)

thanks

nate