xml-dev - Re: control characters

[richard@cogsci.ed.ac.uk (Richard Tobin)]

Rick JELLIFFE <ricko@geotempo.com> wrote:

>If anyone wants to
>encode binary data in XML, they really have to go to bin64 or some other
>encoding like that: XML represented data as text not binary, and control
>codes are not text. 

I disagree strongly with this.  There are purposes such as
configuration files where you may wish to mark up data that contains
control characters, and have those characters be human-readable.

>I think the most that could have been done would have been to make a
>rule that you can represent control characters using numeric character
>references,

That would be reasonable - &#27; may well be more readable than a literal
escape character.

> but that these references are not to be expanded inline
>and/or must be converted back to references when data is generated.

They would have to be converted to references when the data was
serialised, just like & or <.  I don't see any reason why they should
not be passed to the application literally - anything else would
require another layer of processing and not really be any better than
the current situation.

The only character I think it would be reasonable to prohibit even as
a reference is null, because otherise it would be impossible to
represent XML data as plain strings in languages like C.

The workaround I usually suggest is to represent control characters
with (references to) characters from the Unicode private use range.
This makes the necessary transformation a simple character
substitution (which can even be just a subtraction - no need for a
table).

 -- Richard
-- 
Spam filter: to mail me from a .com/.net site, put my surname in the headers.

"The Internet is really just a series of bottlenecks joined by high
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