What is the legend for the objects shown on the map?

What is the legend for the objects shown on the map?

The objects are represented in different ways depending on their category: 

The most famous nebulae are represented by red lines:
The other nebulae are represented by a red ellipse:
Clusters are represented by white ellipses:
Galaxies are represented by blue ellipses:
Stars are represented by yellow dots:
Groups of stars are represented by yellow ellipses:
The objects in the catalog are displayed with a border By tapping on the text, you can get information about the selected object: - If it is a catalog object, you have access to its full name and a link to the object record - Otherwise, you will only see the object's ID and its category