It's NOT Asymmetrical. The XMTS Tartan is Symmetrical. When it was registered, it was listed with the FULL thread count from the first pivot all the way back to that pivot. Most tartans (XMTS included) have 2 pivots... MEANING, if you put a mirror on certain lines, you'll get the exact same thing on both sides.

The 2 pivots for this tartan are the WHITE line and the YELLOW line.