[tz] Proposed patch - Theory notes for backward file

Paul Eggert eggert at cs.ucla.edu
Thu Sep 5 01:48:18 UTC 2013

Stephen Colebourne wrote:
> +The file 'backward' consists of Link entries mapping deprecated names
> +to their replacements. Usage of a deprecated name is discouraged.
> +As such, the file permits canonicalization

We've never said the 'backward' names are deprecated before.
Why start asking users to change names now?  We have no
plans to remove them.

The business with 'canonical' is problematic, given that
we're thinking of letting installers or users filter out
names that are no different pre-1970 (or pre-whatever), and
this may well omit names that would be considered
'canonical' by some.

If we head in this direction, I expect that there will be no
canonicalization that is good for all applications.  Users
who care only about post-1970 timestamps might
consider Europe/Rome to be the canonical name for
Europe/Vatican; users who care only about current and future
timestamps might say Europe/Berlin; and users who
care about political issues (or who assume the Vatican's
secret archives will eventually uncover a local time differing
from Rome's!) might consider Europe/Vatican to be canonical
all by itself.

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