Eliezer,
The problem is that, as far as I am aware, there is no definitive list of these since anyone can add them for any purpose - usually used in conjunction with Custom Handlers.
Often, our developers implement a new feature or workaround using them as this is quicker and easier than adding attributes to the UI (especially if they are of limited interest or for special use-cases) but AFAIK, this isn't something that is centrally coordinated, but gets documented on a case-by-case basis and often referenced from Tech-ref or KB articles.
Sorry!
(Of course, I'm happy to be proved wrong and when I reply like this, I usually am - within minutes, so let's hope that happens here :-D )
Regarding the specific attribute you mention, I will see if I can find anything, but I'm guessing you have already completed an extensive search. Perhaps it would help if you could explain what you are trying to achieve?