Re: Combining characters (was: Re: [idn] hostname historyhell)

[David Hopwood <david.hopwood@zetnet.co.uk>]

-----BEGIN PGP SIGNED MESSAGE-----

Soobok Lee wrote:
> Does a combining sequence inherit the bicameral  characteristic of the
> leading letter ?

It doesn't matter: folding the base character of the combining sequence
is sufficient (usually; <I><dot-above> and sequences that include
Greek ypogegrammeni are exceptions).

> For example,  
>
> <A acute> can be lowercased into <a acute> ?
> Then, <A><acute> ==> <a><acute> ? <A><acute><diaeresis>... ==>
> <a><acute><diaeresis>... ?

Yes.

> Can <I><dot-above> be lowercased into <i><dot-above> or not?

The case-folded form [*] of <I><dot-above> is <i>, not <i><dot-above>.
This only works if the string is NFC-normalised before applying case
folding.


[*] Remember that we are applying case folding, not lowercase mapping.

- -- 
David Hopwood <david.hopwood@zetnet.co.uk>

Home page & PGP public key: http://www.users.zetnet.co.uk/hopwood/
RSA 2048-bit; fingerprint 71 8E A6 23 0E D3 4C E5  0F 69 8C D4 FA 66 15 01
Nothing in this message is intended to be legally binding. If I revoke a
public key but refuse to specify why, it is because the private key has been
seized under the Regulation of Investigatory Powers Act; see www.fipr.org/rip


-----BEGIN PGP SIGNATURE-----
Version: 2.6.3i
Charset: noconv

iQEVAwUBPAE8azkCAxeYt5gVAQFcVQf9Em4jK7x+IjPf/ZKtWPxKS80tmOJIVH2C
11sNkonVdILkcskWHQn/z6nkrXDh/l212AdJN2pMWKEVkbayOu3pB3HDYzo2Inve
Oay4hPIX25jOBqAiaw7QYnHpECMjIQmRft27rK6CrRcF2dtD6cgqByBt5WV4IQH7
S2V5EXD1JBOjCZGKUVioO7z+kZmyS+QvQngbd31D7xiFhEud3kvLK8XX6B6GYQR4
6l+aUHj1TVoxeR5hcExtKia5zC4b/Qa9i0U4hZraS01H0ATiiSavJUtv971cjhFU
fmrg1LSTu+dkPS1yw/AwO82do2Vnf/SLeujLrPqNGgIn2FZEAT2thA==
=2NF+
-----END PGP SIGNATURE-----