spool/BYRR...CG6Q/rx.lock
spool/BYRR...CG6Q/rx/
spool/BYRR...CG6Q/tx.lock
+spool/BYRR...CG6Q/tx/AQUT...DGNT.seen
spool/BYRR...CG6Q/tx/NSYY...ZUU6
+spool/BYRR...CG6Q/tx/VCSR...3VXX.seen
spool/BYRR...CG6Q/tx/ZI5U...5RRQ
@end verbatim
can not contain partly written files -- they are moved atomically from
@file{tmp}.
+When @ref{nncp-toss} utility is called with @option{-seen} option, it
+will create empty @file{XXX.seen} files, telling that some kind of
+packet was already tossed sometime.
+
Only one process can work with @file{rx}/@file{tx} directories at once,
so there are corresponding lock files.