Re: Why is < illegal in an attribute value but the equivalent hex and decimal character entities are legal?

Thanks Pete. That makes sense.

And to be sure that I am crystal clear, when you say:

Internal logic converts "&#x3C;x>blah&#x3C;/x>" to "<x>blah</x>"

The resulting converted value:

    "<x>blah</x>"

does _not_ mean there is an element <x> with value blah. Rather, it means there is a stream of characters '<', 'x', '>', 'b', 'l', 'a', 'h', '<', '/', 'x', '>'  and those characters have no semantics and are not to be interpreted.

Correct?

/Roger

-----Original Message-----
From: Pete Cordell <[email protected]> 
Sent: Thursday, March 17, 2022 7:48 AM
To: Roger L Costello <[email protected]>; [email protected]
Subject: [EXT] Re: [xml-dev] Why is < illegal in an attribute value but the equivalent hex and decimal character entities are legal?

On 17/03/2022 11:25, Roger L Costello wrote:
> So this is perfectly well-formed XML:
> 
> <Test foo="&#x3C;x>blah&#x3C;/x>"/>
> 
> And the numeric character references will be replaced during the parsing process to yield this:
> 
> <Test foo="<x>blah</x>"/>

I'd say that parsing <Test foo="&#x3C;x>blah&#x3C;/x>"/> yields an attribute named "foo" with a value of "<x>blah</x>".

It's not creating an alternate piece of XML that is then parsed again.

The sequence is more like:

- Low level XML tokeniser reads attribute name "foo"

- Low level parse checks it's followed by "=" and quotes

- Low level parser reads until it finds end quote, getting "&#x3C;x>blah&#x3C;/x>"

- Internal logic converts "&#x3C;x>blah&#x3C;/x>" to "<x>blah</x>"

- Internal logic creates a data record for an attribute of name "foo" 
with value "<x>blah</x>" and associates it with the element "Test".

Regards,

Pete.
--
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Pete Cordell
Codalogic Ltd
Read & write XML in C++, http://www.xml2cpp.com
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