If this has already been asked/answered, please direct me.
I build early stringed instruments and I'm drawing up an Italian keyboard instrument (harpsichord) from 1693. Back in the day in Florence, they used a basic unit of measurement called a "soldo" that converts to 27.56 mm by today's metric standard. I would like to figure out a way to define a soldo so I can then use several soldi to lay out the entire instrument, using the soldo as my basic unit of measurement, which would then show up when I turn on dimensioning.
Of course, I could always use metric and label according to the Florentine soldi, but where's the fun in that?