This is a PostgreSQL adapted version of the timezone library
from:

	ftp://elsie.nci.nih.gov/pub/tzcode*.tar.gz

The data files under data/ are an exact copy of the latest data set
from

	ftp://elsie.nci.nih.gov/pub/tzdata*.tar.gz

Since time zone rules change frequently in some parts of the world,
we should endeavor to update the data files before each PostgreSQL
release.

At each update, we should check if time zone offsets have changed.
Just search for the current or previous year and see what has changed.
Sometimes a country changes its time zone offsets, for example Georgia
in 2004.  Just grepping in the zic database files for 2004 is enough to
spot such a change.  Then the files under tznames/ should be updated.