To make the confusion complete: Seeing as the authors are German speakers, they might refer to beer mats as "Bierdeckel", which literally means "beer lid". Yes

To make the confusion complete: Seeing as the authors are German speakers, they might refer to beer mats as "Bierdeckel", which literally means "beer lid". Yes, that doesn't make a lot of sense since they go under the steins. But back in the day, you would drink outside and would primarily want to keep dirt and flies out of your stein, rather than the table clean. So to this day, they're called lids, even though they're coasters (regional variations apply).