XML: why there is no escape (was Re: [xml-dev] What to escape whenserial

[Rick Jelliffe <rjelliffe@allette.com.au>]

I think the terminology "escape" is incorrect, and it is really 
confusing to me.

To escape a character means to do something (typically, to prefix it 
with \ in C-family languages) to allow the character to be used 
literally but without its normal parser treatment.  So \ before a 
newline in a shell script is an escaped character.  An escape sequence 
in older character encodings means you switch the code set (for the next 
character only, for the rest of line, or until the next escape 
sequence): after when you send a particular string (typically starting 
with the ESC character, which is why it is called ESC) you can then send 
the same bytes but they now have the meanings of the new character set.

Having an escape character such as "\", it becomes useful to reuse the 
delimiter as a function signifier, for example that \n mean newline, and 
alternative representation. But this is only escaping in a slack sense.

In XML, the only mechanism like escaping for characters is the CDATA 
section, perhaps. I think it is confusing to speak in terms of escaping, 
because it is used in opposite meaning of what it originally meant. With 
a numeric character reference, you are not escaping a literal character, 
you are using a different method to represent it: in just the same way 
that \n is not a character escape, 
 is neither.

Cheers
Rick Jelliffe