[tz] Fallback rules?

[Alfie John]

Hi TZers,

Sorry if this has been asked before, but I couldn't find any
documentation on the rules of what should happen for the following
circumstances.

Here's the definition for Australia/Brisbane:

  # Rule  NAME    FROM    TO      TYPE    IN      ON      AT      SAVE  
   LETTER/S
  Rule    AQ      1971    only    -       Oct     lastSun 2:00s   1:00  
   D
  Rule    AQ      1972    only    -       Feb     lastSun 2:00s   0     
   S
  Rule    AQ      1989    1991    -       Oct     lastSun 2:00s   1:00  
   D
  Rule    AQ      1990    1992    -       Mar     Sun>=1  2:00s   0     
   S
  Rule    Holiday 1992    1993    -       Oct     lastSun 2:00s   1:00  
   D
  Rule    Holiday 1993    1994    -       Mar     Sun>=1  2:00s   0     
   S
  Zone Australia/Brisbane 10:12:08 -      LMT     1895
                          10:00   Aus     AE%sT   1971
                          10:00   AQ      AE%sT

As the zone ends with AQ, and AQ does not have a "max" ending date, what
should Australia/Brisbane fall back to after 1992? I thought maybe in
this instance perhaps "Aus" as it's the one above it, but "Aus" seem to
oddly be specific to both World Wars. I also don't think that it should
then fall back to a GMTOFF = "10:12:08". That sounds awkward.

Thanks,

Alfie

-- 
Alfie John
alfie at fastmail.com