saddle stitch

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A simple overcasting stitch, usually of a thread contrasting in color with the fabric, used primarily as ornament on clothing.
• noun A stitch used in sewing together the leaves of a book at the fold lines, either with thread or wire.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A stitch in which the center of the fold is placed across the saddle of the stitcher and then wire staples are driven through and clinched on the inside.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a decorative overcast or running stitch, especially in a contrasting color