Austria - significance of writing above the front door?

[HGKinsey]

I was staying in Austria in February and I noticed that above the doors of the hotels was writing in chalk. I assumed that it was something to do with insurance, but a friend thinks it has something to do with it being the period of Lent. Can you tell me what is this custom all about? Many thanks.

[Buenchico]

I found a possible explanation on a website about Christmas(!) in Austria. Although that might appear to be the wrong season, the site states that the letters above lintels can be seen all year round. So, if what you saw read
20 -- K + M + B -- 07
you can get some idea of what it's about here. (Apparently K.M & B are the 3 Kings. It's not stated but I assume that the numbers represent the year. They're 19 and 93 in this article, written in 1993):
http://www.encyclopedia.com/doc/1G1-14970497.h tml

Chris