time-zone designators

[LIVINGSTON Alex]

I am not in favour of alphabetic abbreviations as designators of time 
zones.

First, their role is not well defined. Do they apply to

A: a geographic region and its entire time-offset history and future,

B: a particular single offset from UTC/GMT, or

C: a particular set of two or more offsets from UTC/GMT and "rules" 
describing when changes from one of these offsets to another occur?

Second, there seems to be no requirement for them to be globally or 
historically unique.

I would support two types of time-offset designation:

1: a numeric specification of a single offset from UTC/GMT (e.g. -04:00)

2: a specification applying to a point on the earth's surface and 
indicating the entire history (and expected future history) of the time 
kept at that point by nearby human beings, as in the tz database (as I 
understand it)

Actually, I might also consent to:

1A: a numeric specification of two (or more) offsets from UTC/GMT that 
apply periodically (e.g. +10:00/11:00), though only if such a specifier 
is unique in the context it is used in (+10:00/+11:00 applies both to 
Tasmania and mainland southeast Australia, but the two regions change 
from +10:00 to +11:00 at different times at present, so using that 
label for a zone as things currently stand would not be on)

2A: a specification applying to a well-defined, invariant region of the 
earth's surface and indicating the entire history (and expected future 
history) of the time kept by human beings occupying that region

Type 1 is by far the easiest to work with, and perfectly adequate for 
single-instant specifications. Only if, for a particular geographic 
location, a period of time (including possibly a single date) or a 
repeating scheduled event is to be specified might a single offset not 
be up to the task.

If some apparent standard abbreviated designator is not clear, a lot of 
effort seems to be put into crafting a "suitable" one for the field 
labelled  (for reasons that aren't all that clear to me) "FORMAT" in 
the tzdata files. I get the impression that people derive a sense of 
security from the authority and credibility supposedly lent to time 
specifications by such labels. Only it is a false sense of security, I 
would contend. These abbreviations seem to be seized upon by 
implementors of time-management software as though "official" and 
indispensable and to be appended enthusiastically to time 
specifications. I would like to see such enthusiasm diverted to the 
use, instead, of far less ambiguous and far more informative and 
helpful designators (like type 1 especially).

(I realise now that I have somewhat conflated time zones with time 
specifications. I don't think my comments are affected that much by 
this.)

I hope I haven't strayed into territory outside the purview of this 
list.