Hey,
  To be honest it was something I just threw together as an attempt to learn about NewGRF, I didn't even think about licensing, however I have noticed its becoming quite a big deal at the moment so I will use the Creative Commons Attribution-Non-Commercial-Share Alike 2.0 license found at http://creativecommons.org/licenses/by-nc-sa/2.0/uk/ (http://creativecommons.org/licenses/by-nc-sa/2.0/uk/legalcode).

That should cover just about everything you need ^^
Anthony Boot

> Hi Anthony
>
> currently we're doing an overhaul of the licenses in our #openttdcoop
> grfpack. AFAIK known as antb, you've made the party square. For that there
> does not exist proper license information at least in the places I looked.