I was wondering how many pre-defined group formatting style there is in Mathematica. From Format -> Style, one see that we can go from Title (for Alt+1) to Subsubsection (Alt+6). However, this does not seem to be exhaustive. This is because, if I press Tab on a line created from any of those formattings (from Alt+1 to Alt+6), then I can automatically "move down one level" each time. However, from Subsubsection, it seems that I can still go 2 more levels down, after which Tab does its "normal" job. Are these 2 additional formattings somewhere to be found in some documentation? Are they in any way "special" and can I assign keyboard shortcuts for them as for the other ones?