Hi,
A recent-ish thread[1] made me wonder what that big table of data
does, and why we have a random update every decade or so, and I came
up with the attached.
It's pretty low stakes stuff: it controls where hyphens are inserted.
This happens when new ranges are carved out for publishers, so to pick
an example ISBN plucked from Wikipedia[2], here's an ISBN that is
shown differently after the attached:
postgres=# select '9791186178140'::isbn;
isbn
-----------------
979-118617814-0
(1 row)
postgres=# select '9791186178140'::isbn;
isbn
-------------------
979-11-86178-14-0
[1] https://www.postgresql.org/message-id/flat/e0a62134-83da-4ba4-8cdb-ceb0111c95ce@eisentraut.org
[2] https://en.wikipedia.org/wiki/List_of_ISBN_registration_groups
