In knitting a thread can be run through a row of stitches to keep the stitches from unraveling. It creates a stopping point when you need to unravel.
It's called a lifeline.
In boating terminology is the line that a crew member or passenger on a boat might be attached to so that they don't fall over.
I am starting to add stripes to the "next" sweater, starting with green.
Green for growth.
Green as a lifeline.