Example 2

This example extends example 1 according to the file system. Let's say I'am going to have a lot of pictures in my file system, and I would like to keep track on who have taken the pictures, and the names of the people on the pictures. Again I have 3 pictures, and I have taken the first 2 pictures, my sister have taken the last pictures. The people on the first picture is my mom Ingrid, the next is a picture of my sister Linda and the last picture is a picture of me Allan. I'am going to provide the three pictures with the following metadata: {Allan, Ingrid}, {Allan, Linda}, {Linda, Allan}. As you can see in this example, there is no way of telling who is the photographer and who are the people on the picture. Of course you could change the tags to something like photographer:Allan and people_on_picture:Ingrid but this would be a convention which the user will have to maintain.