You're looking at the wrong Article. 64 says when time off is available. That means when there are lower seniority guys who would otherwise be laid off, higher seniority guys have time off available. Especially if guys are already at the center, browned up and ready to go. It's kinda an unofficial thing here, based on practicality, that we give a minimum half hour notice, because our lay off guys don't actually come to the center (as no one should), because they would be entitled to four hours pay just for showing up. The half hour is so they have time to get ready and get into the center by start time.