Umbrella Etiquette

The weather in Munich is a bit odd this summer (just as it was when we moved to Paris a few years ago). Today it was 60 degrees and raining. So I was forced to walk around with my umbrella propped open - which made me wonder. Is there umbrella etiquette? Specifically, when you approach a fellow umbrella user on the street, are you required to lift, lower or angle your umbrella? Or, are they?