There's a good Freakanomics blog article about trademark enforcement here: <a href="http://www.freakonomics.com/2012/06/26/the-summer-trademark-olympics-please-dont-sue-us/" rel="nofollow">http://www.freakonomics.com/2012/06/26/the-summer-trademark-...</a><p>The takeaway in this case is that aggressive enforcement helps protect a mark holder from losing their claim to the trademark. It seems like you just need to TM those NPS phrases and add some legal notice in your global footer to be in compliance.