What key "shop" includes?

Think of the building as a box(the shop=mall), then you arrange the shop POIs in that box. horizontally or vertically (the floors). If they get too close of each other they wont render, but the data is still there.

There is e.g. shop=mall encompassing all as additional tag to a building marked as e.g. retail or commercial to note a few which then could be called the name the mall was given. Then it's up to the mapper to choose creating the individual points of interest (POI) and place them as close as possible within the building outline as to where a shop can be physically found to include if you'd include their mail addresses add the tag addr:floor = n (so happen to do that today). These POI should not be put on any building line, you'll be told to extract them again and move them in a free space. Certainly I'd not tag the whole building with a name like Tesco if Tesco is just a part.

In the extreme you could map each individual shop in a building and then bind them together in a relation but do not remember to have ever seen this done.

@ Tzorn, over here there's the big Conad chain which runs sub businesses such as the branded Parafarmacia Conad. These are put in a separate POI within the Conad area of operation.

Hi Katerina,

I suggest you read up a bit on the topic in our Wiki. Have a look at the general shops page as well as the shop=* key and the shop=mall and shop=department_store tags. Also look at the discussion pages there for hints on tagging.

You ask about what shop is giving back or returning. Are you asking on how to use some search engine? Which one are you talking about? There are different tagging approaches and a differing degree of details mapped out across our world map. So it is difficult to answer if a pharmacy inside a Tesco would be tagged separately or not. You will probably find both.