Flipped UVs?

Learning UV mapping in Blender. Applying a basic cube layout to a cube with the sides labeled: “top”, “left”, “right”, etc.

Some of them are coming out backwards like “left” here:

http://www.lyzrdstomp.com/images/stories/flippedUV.jpg

Is there a “flip UV” button or something similar? I tried rotate UV, but of course that just rotates it on its center axis. I can unpin it and move 2 of the nodes in the opposite direction and that fixes it, but is there a better way?
Thanks.

Nevermind-found another thread that says to use M for mirror UV. I searched the forum but looked for “Flip UV”. Sometimes it’s just another word. :slight_smile: