I've seen this done in almost every combination imaginable, and would like to know what the 'correct' way to do this is. I've seen the building marked as 'retail' with a point at the pumps for 'gas station' and a point in the building for 'convenience store', I've seen the building itself marked as one with a point added for the other, I've seen the pumps area marked as the gas station and the building marked as the convenience store, and on and on.
Thanks, that did help somewhat. However, it's still a bit ambiguous with 'add a node at the center of the fuel station...' not being clear if that means the building or the pumps or the entire property. (I've seen it all three different ways on OSM), and, of course, it then goes onto say "or create a way around the fueling area." The term 'fueling area' makes me think it may mean the pumps? That's not all that clear again, and I've seen it different ways. I suppose both are okay then, but I was thinking there would be some accepted consistent way to do this. Likewise, for the convenience store it gives both the option of adding a node in the middle of the building and marking that as the convenience store or mark the building itself as the a convenience store.
Sounds like all those options are okay. I suppose I was just being a bit too pernickety about it and wanting there to be a perfectly consistent way to do this.
Decision of micro-mapping a gas station is a matter of how detailed you like it to be and is indirectly asking who will benefit from those details in &OpenStreetMap.
If you think of a large station, it could be made of pumps, shop, technical buildings, parkings, picnic sites, decorative grass, bushes, flower beds, etc.
Then, it becomes clearer the filling area is that: the filling area. So, shop, picnic sites, grass, etc. are part of the gas station but not of the filling area.
Where that area exactly starts and stops is your judgment call based on visual clues like curbs, painted lines, differences in ground surface and elevation, etc.