the explanation of signed dates

I was wondering why these dates were appearing in the piano keys of my 1928 Steinway AIII. Douglas gave me the answer. Evidently it was very common for tuner's to date their work, and usually upside down, which these are. This piano was living in Hawaii so it is interesting to think of what was happening at the time of the tunings. I am working my way through the keys, now I will keep my eyes out for more dates.