Re: Nested entity declarations in DTDs

Hi David,

Thanks for the reply! So the behaviour can change based on whether its internal or external?  That is very good to know now before I back myself into a corner with the implementation.

Is there a reason for that? I was naively hoping that external DTDs could be more or less pulled into the start of the document and carry on as normal.

Regards

Daniel

On 13 Mar 2022, 16:28 +0000, David Carlisle <[email protected]>, wrote:
> You can have the definitions but you can't reference them as you can't have parameter entity references in the internal subset, rxp moans:
>
> $ rxp -sx nes1.xml
> Error: PE ref not allowed here in internal subset
>  in entity "g" defined at line 19 char 1 of file:///c:/tmp/nes1.xml
>  in unnamed entity at line 23 char 4 of file:///c:/tmp/nes1.xml
>
>
>
> If on the other hand you do this in an external DTD it is fine
>
> <?xml version="1.0" encoding="utf-8"?>
> <!DOCTYPE feed SYSTEM "nest1.dtd">
>
> <feed xmlns="&a;">&b;</feed>
>
> where nest1.dtd is
>
> <!ENTITY a 'http://www.w3.org/2005/Atom'>
> <!ENTITY b '&e;&f;&g;&h;&i;'>
> <!ENTITY c 'tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/'>
> <!ENTITY d 'http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/'>
> <!ENTITY e '<title>Obfuscated Atom</title>
>   <updated>2007-10-19T00:00:00+00:00</updated>
>   <id>&c;</id><link rel="alternate" href="&d;"/>
>   <link rel="self" href="&d;1_4.atom"/>
>   <author><name>James Holderness</name></author>'>
> <!ENTITY % a '<entry><title>This is title #'>
> <!ENTITY % b '</title><updated>2007-10-18T23:'>
> <!ENTITY % c ':00+00:00</updated><id>&c;'>
> <!ENTITY % d '</id><link href="&d;'>
> <!ENTITY % e '.html"/><summary type="html">
>   This is the <code>summary</code> for entry number '>
> <!ENTITY % f '.</summary></entry>'>
> <!ENTITY % g '<!ENTITY f "&#37;a;1&#37;b;59&#37;c;1&#37;d;1&#37;e;1&#37;f;">'>
> <!ENTITY % h '<!ENTITY g "&#37;a;2&#37;b;58&#37;c;2&#37;d;2&#37;e;2&#37;f;">'>
> <!ENTITY % i '<!ENTITY h "&#37;a;3&#37;b;57&#37;c;3&#37;d;3&#37;e;3&#37;f;">'>
> <!ENTITY % j '<!ENTITY i "&#37;a;4&#37;b;56&#37;c;4&#37;d;4&#37;e;4&#37;f;">'>
> %g;%h;%i;%j;
>
>
> produces:
>
>
>
> $ rxp -x nes1.xml
> <feed xmlns="http://www.w3.org/2005/Atom"><title>Obfuscated Atom</title>&#10;  <updated>2007-10-19T00:00:00+00:00</updated>&#10;  <id>tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/</id><link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/" rel="alternate"></link>&#10;  <link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/1_4.atom" rel="self"></link>&#10;  <author><name>James Holderness</name></author><entry><title>This is title #1</title><updated>2007-10-18T23:59:00+00:00</updated><id>tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/1</id><link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/1.html"></link><summary type="html">&#10;  This is the <code>summary</code> for entry number 1.</summary></entry><entry><title>This is title #2</title><updated>2007-10-18T23:58:00+00:00</updated><id>tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/2</id><link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/2.html"></link><summary type="html">&#10;  This is the <code>summary</code> for entry number 2.</summary></entry><entry><title>This is title #3</title><updated>2007-10-18T23:57:00+00:00</updated><id>tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/3</id><link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/3.html"></link><summary type="html">&#10;  This is the <code>summary</code> for entry number 3.</summary></entry><entry><title>This is title #4</title><updated>2007-10-18T23:56:00+00:00</updated><id>tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/4</id><link href="http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/4.html"></link><summary type="html">&#10;  This is the <code>summary</code> for entry number 4.</summary></entry></feed>
>
On Sun, 13 Mar 2022 at 15:40, <[email protected]> wrote:
> Hello all,
>
> I was wondering if anyone could help clarify an aspect of the specification for DTDs; I am currently working on an XML parser, but have never really used DTDs myself.
>
> http://www.詹姆斯.com/blog/2007/10/obfuscated-atom
> In the above URL, there is a DTD (copied below) with nested entity declarations, is this valid?
<?xml version="1.0" encoding="utf-8"?><!DOCTYPE feed [<!ENTITY a 'http://www.w3.org/2005/Atom'><!ENTITY b '&e;&f;&g;&h;&i;'><!ENTITY c 'tag:xn--8ws00zhy3a.com,2006-05-04:/tests/atom/obfuscated/'><!ENTITY d 'http://www.xn--8ws00zhy3a.com/tests/atom/obfuscated/'><!ENTITY e '<title>Obfuscated Atom</title>  <updated>2007-10-19T00:00:00+00:00</updated>  <id>&c;</id><link rel="alternate" href="&d;"/>  <link rel="self" href="&d;1_4.atom"/>  <author><name>James Holderness</name></author>'><!ENTITY % a '<entry><title>This is title #'><!ENTITY % b '</title><updated>2007-10-18T23:'><!ENTITY % c ':00+00:00</updated><id>&c;'><!ENTITY % d '</id><link href="&d;'><!ENTITY % e '.html"/><summary type="html">  This is the <code>summary</code> for entry number '><!ENTITY % f '.</summary></entry>'><!ENTITY % g '<!ENTITY f "&#37;a;1&#37;b;59&#37;c;1&#37;d;1&#37;e;1&#37;f;">'><!ENTITY % h '<!ENTITY g "&#37;a;2&#37;b;58&#37;c;2&#37;d;2&#37;e;2&#37;f;">'><!ENTITY % i '<!ENTITY h "&#37;a;3&#37;b;57&#37;c;3&#37;d;3&#37;e;3&#37;f;">'><!ENTITY % j '<!ENTITY i "&#37;a;4&#37;b;56&#37;c;4&#37;d;4&#37;e;4&#37;f;">'>%g;%h;%i;%j;]><feed xmlns="&a;">&b;</feed>
>
>
> Saxon and the XSLT processor in Chrome both say no, but if you try the processor in Firefox it appears to process fine.
>
> http://xsltfiddle.liberty-development.net/jy6KM8g
> Any pointers in the right direction would be appreciated, many thanks in advance. :)
>
> Regards
>
> Daniel