the letters after :0

Hi there, I've looked through procmail manpage and couldn't find an
explanation as to what the different letters you can place after the :0
mean?

I know that

: means use a lock file
B means to use a body search

put I'd like a complete list... if someone could tell me where it is...

(please Cc: any replies to ginof(_at_)io(_dot_)org) thanks!