I have found an interesting patent [1] referenced on this blog [2].
Pay attention to claim number 9.

florin

1: http://blog.digital-scurf.org/2006/11/21#sometimes-patents-amuse
2: http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PG01&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.html&r=1&f=G&l=50&s1=%2220040161257%22.PGNR.&OS=DN/20040161257&RS=DN/20040161257

-- 
If we wish to count lines of code, we should not regard them as lines
produced but as lines spent.                       -- Edsger Dijkstra
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