What does NPN stand for?

What does NPN mean?

NPN	Non Protein Nitrogen Medical » Human Genome
NPN	National Petroleum News Community » Media
NPN	Negative-Positive-Negative transistor Academic & Science » Electronics
NPN	No Purchase Necessary Miscellaneous » Unclassified
NPN	National Prevention Network Community
NPN	New Parents Network Community
NPN	No Point Necessary Miscellaneous » Unclassified
NPN	Nature Photographers Network Miscellaneous » Unclassified
NPN	No Problem Network Computing » Networking
NPN	National Poultry News Community » Media
NPN	Neighborhood Parent Network Miscellaneous » Unclassified
NPN	National Prevention Network Community » Non-Profit Organizations
NPN	New Parents Network Internet
NPN	Negative-Positive-Negative transistor Computing » Hardware
NPN	No Purchase Needed Miscellaneous » Unclassified
NPN	No Purchase Ness Miscellaneous » Unclassified
NPN	No Purchase Nessecary Business » General
NPN	NASA Part Number Governmental » NASA
NPN	Negation, Permutation, Negation Academic & Science » Mathematics
NPN	Nippon Tel.& T. Business » London Stock Exchange