OK,

Thanks darkriver,

I assumed it was something like that...

Your answer is more extensive than I needed but may be of great assistance to others.

I am very familar with the Roman Numeral Relative Chord Notation System because I studied formal music theory for several grades. I was just confused by the '17' '27' & '57' in the fragment below which I now assume means merely 'I7' 'II7' & 'V7'. I'm a little vague mentally at the moment, having a few temporary hassles... :-)

        1                57                1                17
        4                4                1                17
        4                4                1                1
        27                27                57                57

I can now fit it on the Piano Accordion without extra hassles.

Hmmm......

In that case I take it that the system is just an exact copy of the Roman Numeral system for 'uneducated Yanks'* - us older 'British Empire Colonials' (Aussies) having had the Roman Numeral system drummed into us at Primary School ... ;-) Before we had massive imports of US made (by foreigners even) clocks (and before digital clocks), most analogue clock faces in public spaces and many for home use were made with Roman Numerals.

Robin

* or is that really 'uneducated Southerners' ... ;-)
[:-P