Pilsner doilies convey messages
News News blog
The little paper squiggles that are attached to the foot of beer glasses when freshly tapped Pils are known by various names.

Source:
Wunderweib
Some call them "Pils doilies", some "beer rosettes", others "drip catchers".
What is less well known, however, is that these rosettes do not simply catch the drops on the beer glass, but also convey small messages for waiters. It is a normal beer when the logo is facing upwards.
If the logo is turned downwards, it is an Alsterwasser or Radler. This way, waiters who have to bring the beer to the tables can make sure that they distribute everything correctly when several orders are placed.