These derive from ISO-3166, e.g., see 
http://www.din.de/gremien/nas/nabd/iso3166ma/codlstp1/en_listp1.html

There's not a perfect mapping between those Alpha-2 code elements and
Internet ccTLDs, but it's at least 90% correct.

Andy

On Wed, 22 Nov 2000, Carl Wilhelm Soderstrom wrote:

> > Any idea what the ch top-level domain is?
> 
> Switzerland. 'Confederation Helvetica' (I think). hence the 'CH' country
> stickers on Swiss cars in Europe.
> 
> Carl Soderstrom.
>