Hi Gerd,
I found another tag that we don't use: addr:place
This is used frequently, but I don't know if the img format supports it?
addr:place is used instead of addr:street - some addresses don't contain street name but name of village instead. I don't think there is possibility to add points without a road to address search. Often used circumvention for this problem is to give place name to nameless roads in nearby area. Then you can add house numbers to roads and get these addresses in standard address search. City Navigator maps use this solution. Other possibility is to create short artificial road (like 10m) at the point position and add to it place name and house number. This road doesn't have to be routable, only available in search index. This solution is used for transparent maps of addresses. -- Best regards, Andrzej