What is the deadline means in the story?

Deadline are thin, almost invisible twine that are used to hold objects together during construction in space. when constructing things in space. It was strategically used in the battleroom.

"As he sailed through the air, the deadline tautening behind him, he couldn't help thinking: I hope they were right about this wire not being capable of cutting. What a way to end—sliced in half in the Battle Room. That would be an interesting mess for them to clean up. When he was a meter from the wall, the line went taut. Bean's forward progress was immediately halted at his waist. His body jackknifed and he felt he'd been kicked in the gut."