The first USAF dress uniform, in 1947, was dubbed and patented "Uxbridge Blue" after "Uxbridge 1683 Blue", developed at the former Bachman-Uxbridge Worsted Company. The current Service Dress Uniform, which was adopted in 1993 and standardized in 1995, consists of a three-button, pocketless coat, similar to that of a men's "sport jacket" (with silver "U.S." pins on the lapels, with a silver ring surrounding on those of enlisted members), matching trousers, and either a service cap or flight cap, all in Shade 1620, "Air Force Blue" (a darker purplish-blue). This is worn with a light blue shirt (Shade 1550) and Shade 1620 herringbone patterned necktie. Enlisted members wear sleeve insignia on both the jacket and shirt, while officers wear metal rank insignia pinned onto the coat, and Air Force Blue slide-on epaulet loops on the shirt. USAF personnel assigned to Base Honor Guard duties wear, for certain occasions, a modified version of the standard service dress uniform, but with silver trim on the sleeves and trousers, with the addition of a ceremonial belt (if necessary), wheel cap with silver trim and Hap Arnold Device, and a silver aiguillette placed on the left shoulder seam and all devices and accoutrement.

Answer this question, if possible (if impossible, reply "unanswerable"): When was the first USAF dress uniform introduced?
1947