[tz] [PROPOSED] Use "PST/PDT" for Philippine time

[Michael H Deckers]

    On 2018-06-19 19:27, Paul Eggert proposed the changes:

> +# The following alphabetic abbreviations appear in these tables
> +# (corrections are welcome):
   ...
> +#	8:00 PST  PDT*	Philippine Standard Time
...

> +# *I invented the abbreviation PDT; see "Philippines" below.

...

> +# From Paul Eggert (2018-06-19):
> +# I surveyed recent news reports, and my impression is that "PST" is
> +# more popular among reliable English-language news sources.  This is
> +# not just a measure of Google hit counts: it's also the sizes and
> +# influence of the sources.  There is no current abbreviation for DST,
> +# so use "PDT", the usual American style.
> +
>   # Rule	NAME	FROM	TO	TYPE	IN	ON	AT	SAVE	LETTER/S
> -Rule	Phil	1936	only	-	Nov	1	0:00	1:00	-
> -Rule	Phil	1937	only	-	Feb	1	0:00	0	-
> -Rule	Phil	1954	only	-	Apr	12	0:00	1:00	-
> -Rule	Phil	1954	only	-	Jul	1	0:00	0	-
> -Rule	Phil	1978	only	-	Mar	22	0:00	1:00	-
> -Rule	Phil	1978	only	-	Sep	21	0:00	0	-
> +Rule	Phil	1936	only	-	Nov	1	0:00	1:00	D
> +Rule	Phil	1937	only	-	Feb	1	0:00	0	S
> +Rule	Phil	1954	only	-	Apr	12	0:00	1:00	D
> +Rule	Phil	1954	only	-	Jul	1	0:00	0	S
> +Rule	Phil	1978	only	-	Mar	22	0:00	1:00	D
> +Rule	Phil	1978	only	-	Sep	21	0:00	0	S
>   # Zone	NAME		GMTOFF	RULES	FORMAT	[UNTIL]
>   Zone	Asia/Manila	-15:56:00 -	LMT	1844 Dec 31
>   			8:04:00 -	LMT	1899 May 11
> -			8:00	Phil	+08/+09	1942 May
> -			9:00	-	+09	1944 Nov
> -			8:00	Phil	+08/+09
> +			8:00	Phil	P%sT	1942 May
> +			9:00	-	JST	1944 Nov
> +			8:00	Phil	P%sT
>   

    I am disappointed with these changes. The recent modifications
    that removed all "invented abbreviations" have been a step
    forward, but the proposed change is a step backward.

    Database schemas have to define useful representations of
    unknown (or inapplicable) information; SQL has special values
    for that purpose. Inventing ad hoc values that cannot be clearly
    be identified as such is not a good idea, as is well known.

    Following database theory, I consider the numerical
    abbreviations, as introduced into tzdb in 2017 to replace
    "invented abbreviations", a helpful step in making
    the tz database more clearly express what is known
    and what is not. These numerical abbreviations clearly
    indicate that "there is no known generally used English
    alphabetic abbreviation for the time scale
    (but the offset from UT is..)".

    The 2018e version of tzdb thus seems to represent faithfully
    what we really knew at the time about the English acronyms
    used for the Manila time scale (except, perhaps, for the
    acronym used during the Japanese occupation).

    The new information we got about the time scale of Manila
    from Republic Act No. 10535 S. No. 3284 H. No. 164, and
    from google searches, certainly does not apply to the Manila
    time scale in 1899, and it does not even imply that the
    common English acronym, if there was one, for the
    summer time periods in 1954 and 1978 was different from PST.
    But the proposed changes affect all of these aspects.

    I propose to record only what we really have learned since 2018e:
    the abbreviation PST for Manila time was legally acknowledged
    in 2013, and it was used later on by some newspapers.


         Zone     Asia/Manila   -15:56:00 -     LMT     1844 Dec 31
                                8:04:00   -     LMT     1899 May 11
                                8:00      Phil  +08/+09 1942 May
                                9:00      -     +09     1944 Nov
        -                       8:00      Phil  +08/+09
        +                       8:00      Phil  +08/+09 2013 May 30
        +                       8:00            PST

    Michael Deckers.