What are the pharo class icons?

Question

I see different icons for different classes, for example, in this figure:

What does it mean? Some of them, with a red icon, allow me to add comments, but those that have a "c" and a "beam", for example, do not allow me.

The comments mention something about the design of the Class Responsibility Collaborator (CRC), but it is unclear how the comments affect the icon.

Answer 1

An exclamation mark indicates that the class has no comments. Lightning for Exception classes, text bubbles for declaring. Icons with braces for collections and those that have a sigma of capital ( Σ ) belong to classes of quantities (for example, numbers).

Icons with C are for general classes, icons with T are for signs.

There are also classes with a small gray / green / red circle. They show that the methods of this class have a test associated with them and can show whether the entire test passed (green) or not (red). By clicking on this icon, you run all the tests associated with the class methods.