Since April 2008, the German road tagging page
osm.wiki/index.php/De:Germany_roads_tagging
was changed in the way that the refs shall contain spaces now, e.g. A7 shall be written as A 7 now. This might be the correct official notation but it is not consistent with the refs in other countries and also not consistent with the main OSM tagging page (this will, e.g., confuse a newbie badly).

The problem is now that some people try hard to modify existing highways to include the spaces in the refs. Since highways are usually not consisting of just one segment (because of bridges, tunnels, etc.), one has to exchange the ref of all the segments. What I see now is that most segments of a highway were changed but some are not. I see that in some regions there are more spaces, in others are no at all. My opinion to this is that we should not use spaces because this is the way it is done in other countries and this will keep a consistent OSM map.

Recently, somebody has done this "random correction of refs in highway segments" in the area where I did most of the existing mapping. As a consequence, the refs in this area look now very ugly which I do not like at all.

My personal consequence out of this is that I will not tag any new highway I create with a "ref" tag anymore...