What's the purpose of all those various scripts in a WME project

I use the following analogy to describe the scripts/events system in WME:

The game comprises of lots of game objects: scenes, entities, actors, GUI windows and others. Each of the objects has a “body” and a “brain”.

The body is the appearance of the object and it's defined in those various definition files, such as .actor, .entity, .scene and such. These files contain definition of graphics, fonts, the caption of the object etc. Some of the definition files are supported by editing tools (e.g.%