A nice article that explains the history of the military tartans is found on the Scottish Military Historical Society's web site:

http://www.btinternet.com/~james.mckay/disp_020.htm

From this article, it appears that the definition of "universal" in this case refers to the fact that all Scottish regiments at one time wore the government tartan.

Also see this snippet from the SMHS:


Notes on Military Tartan in General.

General Wade having ordered that the pattern and colouring of the plaids for the Independent Companies of Highlanders, later regimented as the Black Watch, should be as nearly as possible uniform, the black, blue and green sett was chosen, which later became famous as the 42nd Black Watch (or Government) tartan.

When further Highland regiments were raised between 1745 and 1800, this sett became the official Government or Military tartan, though it was modified in one or two cases by the addition of a coloured stripe, or stripes, and was not adopted by the 79th or Cameron Highlanders. (Note it also formed the basis of many present-day civilian tartans).

The drummers of regiments wearing this plain tartan usually had a stripe of the Regimental facing colour added, which may have given the idea of the addition of a coloured stripe for the whole regiment where this was adopted. (In some corps, different ranks and appointment were distinguished by a colour stripe, and in those where all ranks had a stripe of the facing colour, that of the drummers was broader than that of the remainder).

Of the Regiments existing in the early 19th century, those who originally made this addition to the military sett were the 71st Highlanders formerly the 73rd or Lord MacLeod's Highlanders (facings: buff), who added a buff and a red stripe; the 78th or Ross-shire Buffs (facings: buff), who added white and red (though owing to their title and facings it is possible that originally the 'white' may have been pale buff, changing later to white as in the case of the 73rd); and the 92nd (facings: yellow), a single yellow stripe chosen by the Duke of Gordon from sample patterns ordered with single, double and treble stripes. The 72nd Seaforths' (so far as known), 74th, 75th, 91st and 93rd retained the plain Military Government sett. For the 79th, Colonel Cameron of Erracht instituted an entirely different tartan, namely, the '79th Regimental' or 'Erracht'.

Cheers!

T.

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