> "19" means the 1900s, the 100 year period (or it could pertain to an event that occurred during the 1900s, it depends on the application, i.e. the definition of the data element taking on that value).
Thanks for this well formulated clarification! The notation "19" may mean different things in different contexts. Let's thus avoid writing too much about "19" and similar notations! Instead, I suggest to try to find new notations to avoid such ambiguities. If we find these (and other) distinctions useful: How will we formulate them?
I am particularly thinking about what I wrote in my two e-mails dated Sat, 7 Nov 2015 and Wed, 18 Nov 2015 where I tried to find out what can not yet be unambigously noted. Which notations will we choose for all these?