vehrmann

`start_date` might also often be stated on a plate/sign. Could be asked along with name of artwork and artist. According to the [OSM wiki](https://wiki.openstreetmap.org/wiki/Tag:tourism%3Dartwork) , this would be "the date...

A thought on `power_supply=*`: when asked, it should be clear if that means a normal power socket e.g. in a building to charge phones etc. or if it means (usually...