There isn’t a list of support Markdown as Stacker doesn’t officially support it, though we have been able to get some “Markdown/Textile”-ish functionality “for free” as part of a 3rd party library we use for rich text, and therefore what’s supported is what’s available in the rich text editor UI there. That said, I would love for us to support the Markdown standard in the future, and we’ll be discussing that along with may other features our our wish lists.