Talk:Standard Generalized Markup Language

Timeline error

The following has, I think, an error (XML came after HTML, no?): "HTML was originally designed based on XML tagging but without SGML's emphasis on rigorous markup." Probably should read: "HTML was originally designed based on SGML tagging but without SGML's emphasis on rigorous markup." MarkVolundNYC 17:43, 5 December 2005 (UTC)

Done. Beinsane 07:24, 11 December 2005 (UTC)

An e-mail with a "history lesson" on the origins of SGML and relation to similar tools of the period: http://people.opera.com/howcome/2006/phd/archive/lists.w3.org/Archives/Public/www-xsl-fo/2002Oct/0076.html John Vandenberg 08:52, 8 October 2006 (UTC)

DSSSL?

As Docbook is (rightly) mentioned, shouldn't DSSSL also be? (MonstaPro 15:41, 2 April 2007 (UTC))

I think not, it's a LISP dialect making the same job as XSLT does. It's not SGML. Said: Rursus ☺ ★ 16:19, 19 June 2007 (UTC)

Actually, DSSSL stylesheets technically are SGML documents, though given how rarely they contain tags I can certainly excuse anyone for not knowing this. More importantly, DSSSL is (as you say) to SGML as XSL[T] is to XML — XSLT isn't important to XML merely because it uses XML syntax, but because of the way it allows one to transform XML trees.

(Incidentally, for some reason standard DSSSL can not actually do precisely the same with SGML — it has the XSL-FO-equivalent baked in, with no SGML infoset to mediate between them. Thankfully, Jade does provide such a facility, which is probably all that matters in practice these days.) --—SamB (talk) 22:28, 5 December 2011 (UTC)

Origin of Abreviation?

Unclear: so does the GML of SGML stand for Goldfarb, Mosher and Lorie or Generalized Markup Language? If it is both that should be mentioned, if its the first it should be cited.

Officially, the "GML" in the name of the IBM product stands for "Generalized Markup Language"; the gloss 'Goldfarb, Mosher, and Lorie' is a quiet little in-joke. (And conceivably an hommage to awk, but probably not.) It would be easy to destroy the humor by making the explanation too explicit. -C.M.Sperberg-McQueen (talk) 21:54, 21 December 2007 (UTC)

It is my understanding that 'Goldfarb, Mosher, and Lorie' was the original name but probably before the macros became an official part of Script. I know that GML was known as Generalized Markup Language when I was using Script in the 1980s when GML was part of Script. Sam Tomato (talk) 18:31, 2 December 2014 (UTC)

Wish: syntax

On the wish list: some more syntax samples, highlighting what looks like HTML and XML, and what's unlike them. Said: Rursus ☺ ★ 16:40, 19 June 2007 (UTC)

I'm searching and searching, but to my dismay most links on SGML are dead, the people having SGML material believing there to be no need to keep maintaining it! Sigh!! Said: Rursus ☺ ★ 17:07, 19 June 2007 (UTC)

Done, got it from DocBook references. Said: Rursus ☺ ★ 18:36, 19 June 2007 (UTC)

Syntax section seemed incomprehensible

To me a language defines a set of documents that are allowable, as does a syntax. SGML is class of languages, right? so I take SGML and a DTD and get a markup language, right? Anyway if I got it completely wrong just destroy it please. But I did not like the way it was written. I would have to stretch my idea of a language too far, or I would feel too lost about what the DTD is doing. Thanks Wikivek 19:53, 30 July 2007 (UTC)

People really abuse (stretch) the meaning of language. Some people say that we can create new languages using XML. I am not familiar with SGML enough to comment further but I agree that the DTDs make things confusing. To the extent that SGML requires a specific syntax regardless of the DTD, SGML is a language. Sam Tomato (talk) 18:44, 2 December 2014 (UTC)

Wish: syntax (2)

I feel the syntax part is asymmetric, describing only a few features that some editor believed were important... (I'm not saying they are not, but there are plenty of other features which are not mentioned). I would vote for collecting a list of features and parts of SGML declaration, in order to start describing them. Rjgodoy (talk) 17:29, 22 January 2008 (UTC)

</QUOTE//

I was also tempted to "fix" this example, but then I realized it was right because.

It shows a net-enabling start-tag followed by a null end-tag. Per ISO 8879:1986/Cor.2:1999(E), K.4.3:

[18] net-enabling start-tag =
 stago,
 generic identifier specification, 
 attribute specification list,
 s*,
 nestc

and, per ISO 8879, 7.5.1.3:

[23] null end-tag = 
  NET 

Wen using the reference concrete syntax, we have:

STAGO <
NETSC /
NET   /

Thus <QUOTE// is the correct form according to the reference concrete syntax.

Note: XML defines NETSC as "/" and NET and ">" so this construct looks as <Quote/> (see note 23 in page 8 of ISO 8879:1986/Cor.2:1999(E)).

However, this article is not about XML. I would prefer to keep examples as close as possible to the reference syntax (it would be a mess if each example uses their own syntax).

I will add a sentence about the XML equivalent of <QUOTE//

See also

Rjgodoy (talk) 18:57, 24 January 2008 (UTC)

XML is not an application of SGML

I changed the xml section to read, "XML is a subset of SGML" instead of "XML is an application of SGML" because the XML spec. does not actually include a normative SGML declaration. (There is a non-normative SGML declaration in the XML 1.0 spec.) --Ott0 (talk) 16:16, 19 April 2008 (UTC)

But it is not a subset either! F.ex. empty clauses like <quark/> are illegal in SGML. Rursus dixit. (^mbork³!) 21:20, 22 February 2010 (UTC)

Annex L of ISO 8879:1986/Cor.2:1999 gives an SGML declaration for XML. However, I'm not sure about namespaces (assuming that ":" is a NAMECHAR). Rjgodoy (talk) 13:55, 20 March 2010 (UTC)

I think it's acceptable to call XML a subset of SGML, given that the first line of XML spec does so:

The Extensible Markup Language (XML) is a subset of SGML that is completely described in this document

In particular, self-closing tags are valid in SGML, under at least two scenarios. First, the null-end-tag delimiter (NET) can be defined as "/>", making <quark /> into the start tag of an empty element "quark" that was closed with the null-end-tag. In full SGML, defining NET this way would also permit, for example, <quark/>content of quark element/>, but that syntax is illegal in XML (using the NET is only legal on empty tags.) If you also include the Web SGML annex, it's even easier, since that defines a NET-enabling start tag close delimiter (NESTC) that is used to close a start tag (instead of the NET itself) in those cases; defining NESTC = "/" and NET = ">" makes <quark/> two tags: the start tag <quark/ and the end tag >, with no content in between. Kutulu (talk) 01:14, 23 February 2011 (UTC)

Less emphasis on syntax, more focus on rationale

I have put in some changes to correct the over-emphasis on minutae of syntax. In particular, I have quoted the standard's Annex A on what generalized markup is, since if you don't understand that you don't understand anything. Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

The article is still missing basic information about simple unfancy markup, but I think it is best to merely redirect the reader to the XML entry, which is being improved in this regard currently. The minutae are more OK in that context.Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

I have added a section on the versions of the standard, in order to clarify the relationship to XML. Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

I have moved the paragraph on its development from the first section to a more suitable place, since it is not appropriate for an introduction. Because I don't want to de-emphasize the individuals who created SGML in making this move, I have also added an extra line mentioning that Goldfarb is the editor.Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

Other suggestions

I am not happy about the description of SGML as a metalanguage in the intro. While it may be true (certainly for original SGML, though not for SGML (WWW) and XML with no DTD or schema) it diverts attention too early on a technical point. I believe that Tim Bray is trying to pitch the vocabulary of XML entry at high-school level, so I think it might be useful to re-work the first intro line in this regard. Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

I think it would be better to have a bullet list giving the three parts to an SGML document and describing each part more clearly. Actually, there can be four parts with the rate link documents, and I think SGML Catalogs deserve a place as an unofficial fifth part too.Rick Jelliffe (talk) 16:21, 10 August 2009 (UTC)

The quotation from IS 8879 Annex A.2 had been altered so it is not longer a quote, and the reference to A.2 somehow become a mythical standard at ISO that was some kind of standard for standards. (The standard for standards is the ISO Directives, now the JTC1 Directives.) So I corrected the quote (and A.2 should be A.1) and put it is a box to show clearly it was a quote. Is that the best format for quotes, or is there something else? Rick Jelliffe (talk) 00:51, 24 August 2009 (UTC)

The introduction is too specific to HTML and does not emphasize its original use for documents. Sam Tomato (talk) 18:09, 2 December 2014 (UTC)

Formal characterization

I have added a section on formal characterization. Rationale follows.Rick Jelliffe (talk) 19:45, 10 August 2009 (UTC)

Since SGML is not used for new systems much, many references to it are more concerned with its theoretical properties than its actual syntactic details. SGML was also subject to much negative response in the 1990s because it did not fit in with simplistic theory and tools: they wanted the horse to follow the cart. Paradoxically, now that XML is so popular, the level of support for SGML-like features in compiler compiler tools and also the exploration of the kinds of theoretical issues that SGML and XML have, have improved this situation quite a bit. The cart is now following the horse, but the horse has died!Rick Jelliffe (talk) 19:45, 10 August 2009 (UTC)

I put in some references to the ISO standard, and I expect to add some more. But this section is weak on citations.Rick Jelliffe (talk) 19:45, 10 August 2009 (UTC)

“Criticisms” section needed

This article is completely uncritical of SGML despite the fact that there are many people who consider SGML a model of what a good standard should not be. There were many well-intentioned but deeply misguided design decisions behind SGML, and huge amounts of people‘s time wasted in dealing with the legacy left behind by SGML. In particular, the fact that HTML4 was formally specified as an SGML application but no actual Web user agents implemented as such has left a real mess behind. For one thing it makes it very difficult (or even impossible) to provide HTML4 validation tools that actually give useful feedback to Web authors without at the same time violating some of the arcane conformance requirements that are in the HTML4 spec only due to it being yoked to SGML misfeatures. — Preceding unsigned comment added by Sideshowbarker (talk • contribs) 01:38, 24 November 2011 (UTC)

I don't think it's fair to blame SGML for the whole "pretend HTML is SGML" mess; isn't that really the W3C's fault? (Fortunately, the WHATWG has somehow pulled the HTML WG's head out of the sand, and HTML5 is actually pretty close to what is implemented and used.) Not sure how this makes useful validation feedback likely to involve violating the HTML4 spec, though: validators aren't exactly required to be silent just because a document is conforming. --—SamB (talk) 00:02, 6 December 2011 (UTC)

Not actually a language

IBM's Generalized Markup Language is not actually a language, it is a set of macros. The Wikipedia page for IBM's GML says it is a set of macros (and I know from my experience with it that it is). I think it is worth mentioning in the history of SGML that IBM's Generalized Markup Language is a set of macros. Sam Tomato (talk) 18:26, 2 December 2014 (UTC)

rigorously defined

In that sentence, rigorously amplifies defined, so a comma is unwanted. TEDickey (talk) 12:08, 1 January 2020 (UTC)

HTML5

HTML was theoretically an example of an SGML-based language until HTML 5, which browsers cannot parse as SGML for compatibility reasons.

I'm not sure that's entirely true; and even if it is, it was true well before HTML5 -- probably since HTML 2.0, but definitely HTML 4.0. It's largely a semantic argument bandied about by purists, basically whether or not something is SGML or XML compliant if it's parsing guidelines are not unforgivably razor strict. Certainly you can make HTML4/5 conform to that strictness and make the purists happy (as if), but in practice, people just don't bother. It's like saying a car with automatic transmission isn't a car (and I know there's people who do say that). - 64.187.160.52 (talk) 18:53, 20 March 2020 (UTC)

• HTML 4 can reasonably be said to be an "SGML-based language". For one thing, it was defined in SGML terms (there's a catalog), and can be processed correctly by SGML tools. There are some additional restrictions in semantics beyond this, such as restricted value ranges for many attributes. Those restrictions cannot be expressed in SGML, but they don't stop a compliant, well-formed and valid HTML 4 document also being SGML . HTML before this? That's just a soup recipe, I barely care.

I haven't been following Usenet since HTML5 came out, so if Yukka hasn't opined on whether it's SGML compliant or not, I wouldn't dare to say! Andy Dingley (talk) 19:45, 20 March 2020 (UTC)

Inserting original research into lede

MOS is pretty clear that the lede should be summarizing the highlights of the topic rather than delving into an editor's disparaging comments founded in WP:OR TEDickey (talk) 18:39, 30 May 2026 (UTC)

I entirely concur. We can't include OR in the lead section, particularly cases like this one that also happen to be factually incorrect. MrOllie (talk) 21:48, 30 May 2026 (UTC)

HTML and XML are not SGML-parseable

I made the following bold claim because someone finally has to say it: "SGML is an obsolete standard"

Of course editors didn't believe me, so I specified why: "Old versions of HTML complied with it but most of the time only in theory. HTML5 is not based on SGML.[1][2]↵SGML does not support XML namespaces.[3][4]↵Thus SGML is not a superset of XML anymore and XML is no longer a subset."

Anyway Tedicky doesn't like it so we need to convince him.

If we don't change this, generations of children will be taught that html and xml are actually sgml in comp sci classes like me, even though they are not and haven't been for many decades in the real world and real sgml actually fell out of use before I was born.

Please help me! ~2026-32191-32 (talk) 20:39, 30 May 2026 (UTC)

It isn't formally an obsolete standard because other standards are still defined in reference to it. If you look at ISO 20022 (XML), for example, it will refer back to ISO 8879 (SGML) and just explain where it differs. As long as the standards are structured like this 8879 will not be obsolete. MrOllie (talk) 21:46, 30 May 2026 (UTC)

The xml standard also claims to be a perfect subset in the spec but it is not. xml namespaces are totally in use in any real world xml scenarios. Like Android developement or svgs generated by inkscape. Sgml has no builtin grammar and thus needs a dtd in order to parse anything. This is not the case for XML. Both have features the other does not have. They are similar languages but that's it. One is not a superset and the documentation referencing sgml won't bring sgml back from the dead. We are using html and xml parsers now. Sgml is irrelevant and not interoperable with xml or html in real world scenarios.

SGML died with its parsers and writers. ~2026-32191-32 (talk) 22:02, 30 May 2026 (UTC)

Sgml parsers made before XML can't even parse <tag />. It's like they added it to the sgml spec to keep the myth alive. But with xml appearing people stopped using sgml anyway. ~2026-32191-32 (talk) 22:23, 30 May 2026 (UTC)

And yet it is not an obsolete standard and won't be in the foreseeable future, because of the way ISO standards interrelate. The article cannot claim otherwise, certainly not based on your personal opinion of the matter. MrOllie (talk) 22:24, 30 May 2026 (UTC)

Can we at least mention that sgml itself is no longer used and that xml and html are not actually sgml applications? Because that's a common confusion. ~2026-32191-32 (talk) 22:29, 30 May 2026 (UTC)

Since that would be factually incorrect, I rather think that would be more confusing. SGML is still in use directly in some contexts (financial systems, for example) and XML is still formally defined in terms of an SGML profile. MrOllie (talk) 22:33, 30 May 2026 (UTC)

HTML5 openly says it is not. Let's start with that. It should be somewhere in the article where people actually see it. ~2026-32191-32 (talk) 22:37, 30 May 2026 (UTC)

HTML 1, 2, and 3 were only sort of SGML, and 5 is in a similar position. It needs a full explanation, which is given in the dedicated section of the article. The lead should remain a short summary of what SGML is, not what it isn't. MrOllie (talk) 22:55, 30 May 2026 (UTC)

"While the HTML syntax described in this specification bears a close resemblance to SGML and XML, it is a separate language with its own parsing rules.Some earlier versions of HTML (in particular from HTML2 to HTML4) were based on SGML and used SGML parsing rules. However, few (if any) web browsers ever implemented true SGML parsing for HTML documents; the only user agents to strictly handle HTML as an SGML application have historically been validators. The resulting confusion — with validators claiming documents to have one representation while widely deployed web browsers interoperably implemented a different representation — has wasted decades of productivity. This version of HTML thus returns to a non-SGML basis."

https://html.spec.whatwg.org/

Big RTFM ~2026-32191-32 (talk) 23:40, 30 May 2026 (UTC)

I really like the "has wasted decades of productivity" part. ~2026-32191-32 (talk) 23:42, 30 May 2026 (UTC)

Please reply. Don't run away from the discussion. ~2026-32191-32 (talk) 19:34, 31 May 2026 (UTC)

See WP:SATISFY. No one owes you a reply to everything you write. MrOllie (talk) 21:23, 31 May 2026 (UTC)

you haven't provided a single argument against anything you just reversed. You literally just spout w3c propaganda from decades ago and insist it is true despite sufficient evidence it is not. You can not make useful xml or html programs with a pure sgml-compliant sgml parser. ~2026-32191-32 (talk) 21:51, 31 May 2026 (UTC)

That you do not agree with my arguments above does not somehow mean that they do not exist. We cannot put your WP:OR into the article. MrOllie (talk) 21:55, 31 May 2026 (UTC)

I was paraphrasing the spec. I have quoted all relevant material. It is not original research at all. Please read the specification or the quoted sections fully before you revert or reply to me. ~2026-32191-32 (talk) 22:28, 31 May 2026 (UTC)

You don't get to place conditions on what people have to do to be allowed to disagree with you. MrOllie (talk) 22:31, 31 May 2026 (UTC)

Article contains lies

Since I got restricted from editing this article over an edit war with MrOllie I will leave my quotes from the html 5 spec here and point out that the spec contradicts the still present sentence in the article: "It does, however, define an alternative XHTML serialization, which conforms to XML and therefore to SGML as well."

== Criticisms ==Neither HTML nor XML can be reliably and fully parsed by a pure SGML parser. HTML has never been parsed as SGML by any browser, HTML5 explicitly defines itself as not based on SGML in the specification and modern XML makes heavy use of XML namespaces (for example Android 1.0 in 2008 already relied on them) which have no equivalent in SGML.The HTML specification further says:

While the HTML syntax described in this specification bears a close resemblance to SGML and XML, it is a separate language with its own parsing rules.Some earlier versions of HTML (in particular from HTML2 to HTML4) were based on SGML and used SGML parsing rules. However, few (if any) web browsers ever implemented true SGML parsing for HTML documents; the only user agents to strictly handle HTML as an SGML application have historically been validators. The resulting confusion — with validators claiming documents to have one representation while widely deployed web browsers interoperably implemented a different representation — has wasted decades of productivity. This version of HTML thus returns to a non-SGML basis.

It also states that the HTML5 XML authoring format (formerly XHTML) is not in application of SGML:

Also, since neither of the two authoring formats defined in this specification are applications of SGML, a validating SGML system cannot constitute a conformance checker either.

~2026-32191-32 (talk) 07:33, 1 June 2026 (UTC)

This is redundant with the above talk section, so I don't anticipate replying here other than to correct a persistent bit of misinformation - XML is indeed SGML. One way we know is from the very first line of the XML specification 'The Extensible Markup Language (XML) is a subset of SGML that is completely described in this document.'. Your persistent WP:OR to claim the contrary is the problem here. Namespaces are not the stumbling block that you seem to think they are.

Whether or not the HTML spec provides a DTD for XHTML5 is beside the point, and that is what they're really talking about. MrOllie (talk) 12:35, 1 June 2026 (UTC)

Xml namespaces weren't part of xml 1.0 thus the xml spec may have been true at the time of writing but not anymore.

"Whether or not the HTML spec provides a DTD for XHTML5 is beside the point"

It isn't about dtds at all. Neither html or xhtml are sgml is what the html5 living spec says. ~2026-32191-32 (talk) 13:21, 1 June 2026 (UTC)

Even if you just insert a CDATA section in an XML document, it won't parse in an sgml parser because SGML requires it to be declared which the valid XML document didn't do. ~2026-32191-32 (talk) 13:53, 1 June 2026 (UTC)

<![CDATA[ ... ]]> does not exist in sgml. ~2026-32191-32 (talk) 14:02, 1 June 2026 (UTC)

That's one type of "marked section", Clause 10.4 of the SGML specification. B.3.5 of the HTML 4.01 spec mentions them as an SGML feature not widely supported by user agents. I argued about a quarter-century ago for Mozilla support, to no effect. Choess (talk) 23:01, 1 June 2026 (UTC)

Okay. I was wrong on the cdata thing. Let's not move the goal. Xml namespaces are not sgml even though they parse but as one name rather than as namespace. You can't really call it a subset anymore. ~2026-32191-32 (talk) 08:53, 2 June 2026 (UTC)

"A subset is a set whose elements are all members of another set. In other words, a subset is a part of a given set. If A and B are two sets, we say A is a subset of B if every element of A is also an element of B."

XML namespaces (element of A) is not part of SGML (B). ~2026-32191-32 (talk) 09:14, 2 June 2026 (UTC)

I'm broadly sympathetic to your overall point: the fact that XHTML5 documents are "fully-tagged SGML documents" (as is all well-formed XML) is Technically Correct, The Best Kind of Correct. It doesn't really speak to the niche status of generalized SGML systems, which has really always been the case. But ultimately the way to carry this is going to be to find a reliable secondary source (surely there's an O'Reilly book or something with an introductory chapter on the history of markup languages?) and conform to the claims it makes about SGML and XML. That's probably going to result in more nuanced language than "obsolete" but will provoke less debate. Choess (talk) 13:16, 2 June 2026 (UTC)

Yes, exactly. The best way to avoid WP:OR is to find a good secondary source and stick to it closely. MrOllie (talk) 14:01, 2 June 2026 (UTC)

Hold on right there. The HTML5 spec says xml authoring format is not sgml. The following .xhtml file renders a circle in firefox.

<html xmlns="http://www.w3.org/1999/xhtml"      xmlns:svg="http://www.w3.org/2000/svg">  <body>    <svg:svg width="100" height="100">      <svg:circle cx="50" cy="50" r="40"/>    </svg:svg>  </body></html>

~2026-32191-32 (talk) 14:18, 2 June 2026 (UTC)

The same is true for this. It can't be done without namespaces.

<html xmlns="http://www.w3.org/1999/xhtml"      xmlns:a="http://www.w3.org/2000/svg">  <body>    <a:svg width="100" height="100">      <a:circle cx="50" cy="50" r="40"/>    </a:svg>  </body></html>

~2026-32191-32 (talk) 14:26, 2 June 2026 (UTC)

The HTML5 spec is not a 'good secondary source'. We cannot put your interpretations of the spec into the article. That is the root of the WP:OR problems I keep referring to. Maybe you're right about namespaces, maybe you're wrong. It doesn't matter because you aren't providing a reliable secondary source. MrOllie (talk) 14:50, 2 June 2026 (UTC)

For what exactly?

https://thisvsthat.io/sgml-vs-xml

says sgml doesn't have namespaces and xml does

https://doc.qt.io/qt-6/xml-namespaces.html

says qt xml uses namespaces

You will not find a secondary source saying xml is not sgml because xml doesn't receive updates and it's a pretty controversial to say that and oppose established teachings that solidified over the last 28 years. Just look at me arguing against the world. Only html and xhtml receive updates, so the whatwg said they are not sgml because it's within their "jurisdiction". However saying modern xml is sgml is nothing but a lie everyone repeats because it doesn't fucking work in an sgml parser since they don't support namespaces which is essential to modern xml files. ~2026-32191-32 (talk) 15:10, 2 June 2026 (UTC)

You will not find a secondary source saying xml is not sgml because xml - Then it stays out of the article. That's what Wikipedia's policies require. oppose established teachings that solidified over the last 28 years - For better or worse, Wikipedia's purpose is to repeat and summarize established teachings. You won't have any success trying to change them here. WP:RIGHTGREATWRONGS. MrOllie (talk) 15:32, 2 June 2026 (UTC)

However at least the xhtml5 being sgml needs to be corrected. You have the spec saying that, so your own uncited deduction that xhtml is sgml is wrong and opposes the spec. ~2026-32191-32 (talk) 15:58, 2 June 2026 (UTC)

You are interpreting the spec in that way, but I don't concur with your interpretation, particularly in light of other sources who are stating differently. More secondary sources would be required to change the article. MrOllie (talk) 16:04, 2 June 2026 (UTC)

"For compatibility with existing content and prior specifications, this specification describes two authoring formats: one based on XML, and one using a custom format inspired by SGML (referred to as the HTML syntax). Implementations must support at least one of these two formats, although supporting both is encouraged."

"Also, since neither of the two authoring formats defined in this specification are applications of SGML, a validating SGML system cannot constitute a conformance checker either."

What part do you not understand? ~2026-32191-32 (talk) 17:09, 2 June 2026 (UTC)

I don't understand how I can be any more clear about requirements for secondary sourcing - You keep coming back with quotes of the primary source which might nor might not mean what you think they mean - they certainly do not support the changes you'd like to make to the article, not without WP:OR. Since we are just arguing in circles and repeating ourselves, I do not anticipate replying again unless someone has something new to say. MrOllie (talk) 17:17, 2 June 2026 (UTC)

I suggest modifying the last 2 sentences of the "HTML" section of the article as follows to more accurately describe the relationship between HTML5 and SGML. Choess (talk) 01:00, 3 June 2026 (UTC)

Although HTML syntax closely resembles SGML syntax with the default reference concrete syntax, HTML5 abandons any attempt to define HTML as an SGML application, explicitly defining its own parsing rules, which more closely match existing implementations and documents. HTML5 provides an alternative XML syntax for the language, but no DTD. All well-formed XML documents are conforming SGML documents, but the XML syntax of HTML5 is unmaintained and no future updates for it are planned.