A good description is:

http://www.clanhannay.us/sash.html

Men, on the other hand, can (and should) wear their "sash" -- fly, half (Drummer's) , full (Piper's) or untailored (shawl or "blanket") plaid--- upon shoulder opposite their dominant or writing hand with a (strong cultural) preference to left. Historically it would be, as with the shield in jousting, the left shoulder. While the days of forced use of the right by lefties is, for the most part, behind us even today most countries continue a bias in favor of right handedness due to its dominance--- recall, however, that not all languages are written left to right but many right to left and still others top down. The middle English word for left is "sinistre" with all its other meanings (including unlucky).