As things happen I had a look at one of the hundreds of advertising mails we all receive everyday and as it looked interesting thought to post it here ask ask your opinion.
http://www.permanentmark.nl/en-algemeen.htm FREELANDER 2 TD4 SE (XS UK) IZMIR BLUE SIDE STEPS COLD PACK BI-XENON TINTED WINDOWS - AND PROUD OF HER

I think it looks a good idea, its been around for a while now, my caravan has all its windows marked in the same way with it CRIS number.

I have had all my electronic at home marked with Liquid DNA, which looks like a small dab or line of clear nail varnish, but it illuminates under UV light and the colour identifies it mine. Former Mod/Member, with the most post & Chicken George Arch nemesis