Not sure anyone cares about this (because no replies) but I finally found this info in the Chinese version of the documents.
(When a new file is created, assetDB will send this event.)
(This event is sent if a file is moved within the project folder.)
(This event is sent when a file is deleted.)
(If the file is modified, this event will be sent.)
(This event notification is sent when an error occurs while importing a script.)
(This message will be sent when the scene enters the prefab edit state)
(When the scene is saved, it will send the message)
(This message is sent when the scene is refreshed for special reasons)
(When the scene is ready it will send this message)
(It will send this message when it begins to compile)
(It will send this message when it is done compiling)
(When the compiler state is changed, this message is sent)
(When the build options are viewed)
There is more info on the page about some hidden messages that are sent to open panels and the like. You can check it out at the page address linked above and translate using Chrome / Google Translate.I find that there is much more info in the Chinese version of the docs, and am learning things, even with spotty translation.