On Wed, Jul 22, 2009 at 10:47:54PM +0200, Alexey Melnikov wrote:
My understanding is that prohibited characters are never generated
during mapping.
Nonetheless, it's simpler to prohibit their output than it is to
prohibit them in the input _and_ check that all other mappings and
transformations cannot produce these codepoints in the output.
And it doesn't hurt to say that we prohibit their output even though in
practice it's best to think that we prohibit them as input.
At most a sentence, to say just that, would be appropriate ("by
prohibiting these codepoints in the output we effectively prohibit them
in the input").