Introduced shortly after the appearance of the dreaded Gundams, OZ's newest mobile suit, the OZ-12SMS Taurus was a truly advanced unit, being designed primarily for space combat but also serving well as a transformable fighter in atmosphere. Its mobility and high speed made the Taurus one of the most respected and feared mobile suits to be developed by OZ. Last, and certainly not least, the Taurus is equipped with the Romefeller Foundation's "mobile doll system," an artificial intelligence system which enables it to fight with lethal efficiency even without a human pilot.

Though it would eventually be supplanted by the first dedicated mobile doll unit, the OZ-02MD Virgo, the Taurus would find its way into the service of many factions, including the White Fang revolutionary army, the defense forces of the pacifist Sanc Kingdom, and even the secret Mariemaia Army the following year. OZ's own Taurus mobile suits are colored black. When Relena Peacecraft re-establishes the Sanc Kingdom, her aide Lucrezia Noin secretly assembles a corps of white Taurus units, which are the only ones ever seen fighting in Earth's atmosphere - it's not clear whether they've been specially modified for this purpose. And when the space colonies form the White Fang resistance movement, their apparently colorblind leaders come up with a distinctive new color scheme for their captured Taurus mobile suits.

Source: Gundamproject.com, New Mobile Report Gundam Wing