Baffling math problems [Was: HTML 3.0 DTD ]

Daniel W. Connolly (connolly@hal.com)
Fri, 02 Dec 1994 17:54:31 -0600


In message <9412011847.AA16501@dragget.hpl.hp.com>, Dave Raggett writes:
>For those of you having problems with "hplose.hpl.hp.com" you can now
>get the HTML 3.0 DTD direct from the CERN technical page for HTML:
>
> http://info.cern.ch/hypertext/WWW/MarkUp/MarkUp.html
>
>The review paper and DTD for HTML+ is also there, see
>"Dave Raggett's presentation slides on HTML+ from WWW'94"

I've been doing some testing with the HTML 3 DTD.

Firs, to make sure HTML 3 meets the following stated design goal:

o Backwards compatibility with 2.0

I gave Dave some feedback earlier, and this design goal is nearly met.

I have had to tweak the html3.dtd file a little to get it to work
for my purposes:

===================================================================
RCS file: /u/connolly/cm/web/html-test/htmlplus/html3.dtd,v
retrieving revision 1.2
diff -u -r1.2 html3.dtd
--- 1.2 1994/11/30 18:26:30
+++ html3.dtd 1994/12/02 23:15:17
@@ -72,7 +72,6 @@
could also be handled via refining the URL syntax.
-->

-<!DOCTYPE HTML [

<!ENTITY % HTML.Version
"-//IETF//DTD HTML 3.0//EN//"
@@ -197,9 +196,14 @@
of characters in widely available Latin-1 fonts, and as such
is a mixture of ISOlat1 and other ISO publishing symbols -->

-<!ENTITY % HTMLlat1 PUBLIC
- "-//IETF//ENTITIES Added Latin 1 for HTML//EN">
-%HTMLlat1;
+<!ENTITY % ISOlat1 PUBLIC
+ "ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML">
+%ISOlat1;
+
+<!ENTITY amp CDATA "&#38;" -- ampersand -->
+<!ENTITY gt CDATA "&#62;" -- greater than -->
+<!ENTITY lt CDATA "&#60;" -- less than -->
+<!ENTITY quot CDATA "&#34;" -- double quote -->

<!--================ Entities for special symbols =========================-->

@@ -218,17 +222,21 @@
<!-- a range of standard icons such as &folder; for use
in speeding up display of directory listings etc. -->

+<!--@@
<!ENTITY % HTML-icons PUBLIC
"-//IETF//ENTITIES icons for HTML//EN">
%HTML-icons;
+-->

<!--================ Entities for math symbols ============================-->

<!-- ISO subset chosen for use with the widely available Adobe math font -->

+<!--@@
<!ENTITY % HTML-math PUBLIC
"-//IETF//ENTITIES Math and Greek for HTML//EN">
%HTML-math;
+-->

<!--=================== Text Markup =======================================-->

@@ -297,7 +305,7 @@
-->

<![ %HTML.Deprecated [
- <!ENTITY % linkName "name NAME #IMPLIED -- named link end --">
+ <!ENTITY % linkName "name CDATA #IMPLIED -- named link end --">
]]>

<!ENTITY % linkName "">
@@ -1021,5 +1029,4 @@
>

<!-- The END -->
-]>

Other than that, it seems to be a pretty clean superset of the 2.0
DTD.

Then I started validating some of the "Welcome to Arena" documents.

I have added the html3 dtd to the validation service so you can check
stuff for yourself.

http://www.hal.com/%7Econnolly/html-test/service/validation-form.html

I found a few easily explained boo-boos and typos, but then I found
one that really baffled me.

Here's the one that baffles me:

http://info.cern.ch/hypertext/WWW/Arena/tour/math2.html

sgmls: SGML error at -, line 19 at ">":
BOX end-tag implied by OVER start-tag; not minimizable
sgmls: SGML error at -, line 19 at ">":
MATH end-tag implied by OVER start-tag; not minimizable
sgmls: SGML error at -, line 19 at ">":
TABLE end-tag implied by OVER start-tag; not minimizable
sgmls: SGML error at -, line 19 at ">":
Out-of-context OVER start-tag ended HTML document element (and parse)

The offending line is:

<td><math>{(<left>e^ax^<over>1+{1<over>x}<right>)}</math>

I can't figure out why <over> is out of context there. It looks fine
to me!

Dan