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Re: Couldn't illegal XML characters be used simply byescaping

• From: Liam R E Quin <liam@w3.org>
• To: "Costello, Roger L." <costello@mitre.org>
• Date: Sat, 10 Nov 2012 11:31:17 -0500

On Sat, 2012-11-10 at 13:08 +0000, Costello, Roger L. wrote:
> Hi Folks,
> 
> This week I was in a discussion and the topic of illegal XML
> characters came up and someone asked: "Couldn't illegal XML characters
> simply be escaped?"

You have to be careful with terminology here: there's more than one
level of escaping.

(1) numeric character references can only be used to "escape" characters
that are legal in XML, but might have another interpretation if not
escaped, such as & or <, or such as non-ASCII characters in environments
that are not fully 8-bit-clean.

(2) application-layer escaping, in which the XML processing system isn't
even aware that a character is being escaped (like my crazy UCODE scheme
that allows you to escape characters like NUL or space even inside
element names).

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
Pictures from old books: http://fromoldbooks.org/
Ankh: irc.sorcery.net irc.gnome.org freenode/#xml
Co-author, 5th edition of "Beginning XML", Wrox, 2012

• References:
  • Couldn't illegal XML characters be used simply by escaping them?
    • From: "Costello, Roger L." <costello@mitre.org>