I is the major chord.....whichever key is specified. IV is the augmented chord, VII is the dominant seventh chord......I forget what V is......(I is a fiddlerand chords don't mean much to me) It's just "theory" stuff.......do you understand "standard progression"? Say, "Standard chords in G major"? That is all it is.....if that makes sense. VIII (8) would be an octave chord from the main I (one).......I have no clue how "weird" chords fit into the 1-8 numbering system. I suspect they don't. I imagine they have to be specified--such as "That's an F#m there".........