In the U.S. - seniority list is updated monthly. You can see who's removed. Their names are still on list with removal code next to the name. Every year a 'new' list is published and the prior year's retirees/fired/quit disappear.
Company also posts a monthly retirement list. Probably out Monday/Tuesday since it typical takes a couple of days. Monthly update to your effecitve seniority list - IE, you're #2000, 20 guys retire in April, effective seniority is updated in early May to reflect you're now #1980.