From: Tanaka Akira <akr@...>
Date: 2013-07-13T22:07:00+09:00
Subject: [ruby-core:55995] Re: [ruby-trunk - Bug #8630][Open] Transcoding high-bit bytes from ASCII-8BIT to a text encoding should be :invalid, not :undef

2013/7/13 "Martin J. D�rst" <duerst@it.aoyama.ac.jp>:

> That's one way to put it, but a better way is to say that ASCII-8BIT
> consists of 128 ASCII characters and 128 unassigned codepoints. This is
> similar to unassigned codepoints in UTF-8.

Your interpretation forbids us to convert binary between encodings.

For example, Emacs has charsets for binary such as eight-bit-control or
eight-bit-graphic (or eight-bit?  I'm not familier with recent Emacs).

If we support a encoding which supports them and ASCII, we can convert
binary string between the encoding and ASCII-8BIT.

In your interpretation, such conversion would raise
UndefinedConversionError because unassigned codepoints can't have
character mapping for another encoding.
-- 
Tanaka Akira