I think a lot of it depends on when a tartan was designed -- newer District, Organisational, etc. tartans tend to have meanings behind their colours, but older tartans do not. This especially applies to District Tartans.

One that instantly comes to mind is the Nova Scotia Tartan, one of the first District Tartans outside of Scotland (and my wife's tartan!):

http://www.gov.ns.ca/legislature/HOU...ols/tartan.htm

If you can get a copy of "District Tartans" by Teal and Smith, it explains the symbolism of many of the tartans listed -- but is a very pricey book, but worth every penny!

Cheers,

T.