In my opinion it would be useful to indicate the material of the bus stop shelter – especially if it is made out of glass. But I don’t see a way to do this, all I found is building:material but its description states it requires a building while I have just a bus stop.
So how should I mark the material (I exclude comments and alike because they are not suitable for automatic processing such data later on).
I think it’s a interesting proposal.
But, please give us some examples of how we can use it.
Various materials are used for bus stops in modern big cities.
I think it is difficult to define it as one.
Floors, roof, chairs, columns, walls(Even the walls are made of a mixture of materials.), and various devices and facilities included there…
Honestly I think the general description as given for building is sufficient: Key:building:material - OpenStreetMap Wiki For example take a look at the glass and mirror glass section – nobody would expect the building is literally made of pure glass, yet the term “glass” is used and I think it is well understood what it means. Similar to bus stop shelter – when I would use term “glass” my understanding would be the major elements would be made of glass, and not literally every screw or nail was made with glass.
As for being beneficial, I had in mind (but forgot to mention it, sorry) bus stops outside cities. You know, in a city you will survive, but somewhere in forgotten area the bus stop shelter could serve as a true shelter (for a night for example). So the information of the material is important (glass shelter overheat and at least in Poland are notoriously destroyed, so basically they don’t offer proper protection).
My English is terrible, so I think it caused some misunderstanding. I’m really sorry.
I think it is important what to consider as the main material based on how to use the feature information.
Likewise, that’s why I asked how it could be used.
Is it difficult to implement a method to mark all the facilities included in the bus stop facilities with a check mark? (Multiple selection)
I have never seen feature information that supports multi-selection yet.
Perhaps it is because this method is difficult to implement, but if this method is possible, this method will be quite useful.
I think you are right, in considering bus stop shelters not buildings. I’d say, they are street furniture. That is what they are called in trade. They come in some variety, eg. Bus stop shelters - Street Furniture STREETPARK shows some. Just plain material=glass|wood should be sufficient. Support structure almost always metal, walls and roof likely the same material.
I am lost here a bit. I meant dominant material used in bus stop shelter.
And one thing would be how such data are provided, the other one how it would be shown to user when editing data or viewing it – but the latter is quite different story, because without data there is nothing to edit, and even with data each editor/view could shape its UI differently without impacting the data.
@Hungerburg thank you for your example, but also let not forget this is an example, in real life the bus stops can look like little buildings (or bunkers 
) – built on spot, not transported, with brick or wood.
Anyway, the more I think about it, I come to conclusion we could use something like this:
shelter:material=wood,brick
shelter:roof=wood
shelter:front=wood
shelter:back=wood
shelter:side_walls=brick
even using the first line (when somebody is in a hurry, lazy, not sure, etc) would be useful, but if someone would like to be precise there would be means to specify all five faces of the shelter.
I am note sure if the specifying faces/parts is really necessary, it could be an overkill for such small object :-).
nobody would expect the building is literally made of pure glass, yet the term “glass” is used and I think it is well understood what it means.
on the other hand, there are buildings made entirely of glass and there’s no obvious way to map it.
@dieterdreist of course it is not up to me to decide, but I would say the driving factor should be usefulness not absolute perfection (of course if the latter can be achieved, great, my point is – let’s not kill usefulness because it might be somewhat imprecise).