See also this page for more information on couverte braids.
“Couvert” or “couverte” was the term used in the 15th C. loop braiding manuscripts for a double-tubular braid – one tubular braid closely encased by a second tubular braid, both braided simultaneously.
Such braids can be made in several different forms and using various numbers of loops, either by a single braider or by a team of two or more cooperating braiders.
A track-plan diagram is both a cross-section view of a braid’s shape, and also a road map of how the strands interlace. Aside from looking cool, they can be useful even if you don’t totally “get” them. Even a little familiarity with them can help you better understand what you’re braiding.
Loop Braiding 