Main line
In a suspension, the upline that carries most of the load, usually the one protecting the head, neck and chest; Shibari Study notes it should come off last.
Main line is the name for the suspension line, or upline, that takes the largest share of the weight in a suspension. Shibari Study explains that it is usually the line that protects the head, neck and thorax, and that it should be the last rope removed when someone is brought down. Anatomie Studio lists main line together with upline and suspension line as names for the rope that connects the tied person to the suspension point.