Rename "XHTML parsing" etc to more-accurate "XML parsing"

[sideshowbarker]

See #2056 (comment)

The current Parsing XHTML documents, Serializing XHTML fragments, and Parsing XHTML fragments sections define requirements for XML processing, not anything specific to “XHTML”.

And in general continued use of the term “the XHTML syntax” buys us nothing at this point, so the change in this PR replaces all references to that with just “XML”.

When most authors see the term “XHTML document” they think about XHTML1, not about anything we define in the current HTML spec. It’s ambiguous. So this change clears away that ambiguity.

[domenic]

I think there's a worthy goal here in clarifying that certain parts of the spec currently say "XHTML" but are meant to apply more broadly to all XML in web browsers. However, I'm not sure I'd go as far as this PR does in attempting to eradicate the concept of XHTML entirely. (Also I think it's worth being careful about how you phrase things to avoid pitchfork-wielding mobs; you're not "retiring XHTML" in the sense of asking browsers to get rid of it; you're phasing out the name XHTML.)

In my opinion the name XHTML is still useful, to clarify that we're talking about a specific XML vocabulary. To the extent people think about standards at all when using the word XHTML, I disagree that they think about XHTML1; I hope that most people are aware that the HTML Standard is what defines XHTML these days as something that swallowed both the HTML4 and XHTML1 efforts.

Concretely in terms of this PR, I think most of the changes then are not good, as they just remove specificity. It requires a lot more care to go through and find which parts of the spec are actually talking about XML in general as opposed to the specific XHTML vocabulary. At a glance, the "parsing XHTML documents" and "serializing XHTML fragments" sections are the most obvious changes, but most of the others I find in the PR I'd rather not change.

[domenic]

In my opinion the name XHTML is still useful, to clarify that we're talking about a specific XML vocabulary.

Stated another way, the changes in this PR seem tantamount to me to replacing all mentions of "SVG" with "XML".

[annevk]

I don't think it's quite the same as that. The vocabulary is HTML and there's an HTML and an XML syntax. This is true for SVG too. The vocabulary is SVG and there's an HTML and an XML syntax.

Giving the vocabulary a different name in XML is rather weird and mostly a historical thing because it was new at the time and the focus back then was much more on syntax than systems.

[domenic]

I see your point. Maybe it's just what I'm used to, but I still think there's value in having a simple name like "XHTML" for "the XML syntax of HTML", and using that in various sections in the spec.

[sideshowbarker]

Stated another way, the changes in this PR seem tantamount to me to replacing all mentions of "SVG" with "XML".

It seems to me that’s not apt, for the same reasons pointed out in #2062 (comment).

To me it seems the way we’re using the “XHTML” label is similar to using a special name like “HSVG“ or whatever to label the case of SVG is embedded in a text/html document rather than an XML one.

I think it's worth being careful about how you phrase things to avoid pitchfork-wielding mobs; you're not "retiring XHTML" in the sense of asking browsers to get rid of it; you're phasing out the name XHTML.

You’re right—I’ve changed the issue title now to be less provocative. (And thanks for calling me on that—it’s counterproductive to be flame-baiting here.)

I still think there's value in having a simple name like "XHTML" for "the XML syntax of HTML", and using that in various sections in the spec.

I strongly agree there would be if we had evidence showing we have a lot of authors who are actually doing that. But the evidence we actually have shows the opposite.

I’ll post another comment with the details, but in the mean time, I want to explicitly assert something implicit in me raising this PR to begin with—which is: I don’t think the underlying use case is common enough or important enough to merit us continuing to give it a special label.

[domenic]

To close the loop here, I withdraw my objection, but I don't wan't to be the one reviewing this since my instinct is just to leave things as they are, so I'm not a good judge of whether each of the changes is correct.

I think we may want to be more careful about preserving the auto-generated IDs, however. And changing the split-filename has a lot of consequences; either we need to create a redirect, or we should just leave it as-is as a historical note.

[zcorpan]

In general I think this is fine, but the prose needs some tweaks here and there and we shouldn't change filenames or ids.

[zcorpan]

I think this changes the expectation about what this section is about, from "HTML as text/html vs HTML as XML" to "HTML vs XML the meta language".

[annevk]

Maybe "HTML vs XML syntax"?

[annevk]

I think in this section we should add a note that HTML's XML syntax was formerly known as XHTML, but that we decided to abandon that terminology since it does not exist for MathML and SVG either.

[annevk]

I think as we transition it's important to acknowledge that XHTML was indeed a thing of sorts.

[sideshowbarker]

-  <h3>HTML vs XHTML</h3>
+  <h3>HTML vs XML</h3>

I think this changes the expectation about what this section is about, from "HTML as text/html vs HTML as XML" to "HTML vs XML the meta language".

Agreed yeah the change is misleading as is.

Maybe "HTML vs XML syntax"?

I changed it to “HTML syntax vs XML syntax”.

I think in this section we should add a note that HTML's XML syntax was formerly known as XHTML, but that we decided to abandon that terminology since it does not exist for MathML and SVG either.

I think in this section we should add a note that HTML's XML syntax was formerly known as XHTML, but that we decided to abandon that terminology since it does not exist for MathML and SVG either.

I added a note saying that.

[zcorpan]

This is fine.

[zcorpan]

fine

[zcorpan]

fine

[zcorpan]

fine

[zcorpan]

I suppose we still want to require support for Namespaces in XML for UAs that support XML?

[annevk]

Yes, I don't think we should remove this. In fact, we have numerous dependencies on XML/XMLNS in the platform. I doubt it's really optional.

[sideshowbarker]

-    <p>Implementations that support <span>the XHTML syntax</span> must support some version of XML,
-    as well as its corresponding namespaces specification, because that syntax uses an XML
-    serialization with namespaces. <ref spec=XML> <ref spec=XMLNS></p>

I suppose we still want to require support for Namespaces in XML for UAs that support XML?

Yes, I don't think we should remove this. In fact, we have numerous dependencies on XML/XMLNS in the platform. I doubt it's really optional.

Restored

[zcorpan]

Don't change the filename or the id.

[sideshowbarker]

+  <h2 split-filename="xml"><dfn>XML</dfn></h2>

Don't change the filename or the id.

OK, restored those

[zcorpan]

id="parsing-xhtml-documents"

[sideshowbarker]

id="parsing-xhtml-documents"

Added

[zcorpan]

don't change the id

[sideshowbarker]

-  <!--en-GB--><h3 id="serialising-xhtml-fragments">Serializing XHTML fragments</h3>
+  <!--en-GB--><h3 id="serialising-xml-fragments">Serializing XML fragments</h3>

don't change the id

OK, reverted the id

[zcorpan]

id

[sideshowbarker]

-  <h3>Parsing XHTML fragments</h3>
+  <h3>Parsing XML fragments</h3>

id

Added

[annevk]

I'm also in favor of this. I added some minor comments on top of those of @zcorpan.

[annevk]

Looking good.

[annevk]

We should preserve the ID here. Also, "HTML vs XML syntax" seems more natural?

[sideshowbarker]

-  <h3>HTML vs XML</h3>
+  <h3>HTML syntax vs XML syntax</h3>

We should preserve the ID here.

oofs, yeah—fixed

Also, "HTML vs XML syntax" seems more natural?

Yes, quite clear in the context—changed to that

[annevk]

Maybe "no such term is used for the HTML syntaxes of MathML and SVG"?

[sideshowbarker]

Maybe "no such term is used for the HTML syntaxes of MathML and SVG"?

OK—changed it to that

[annevk]

Why was this ID added by the way?

[sideshowbarker]

Just so there would be something to point to for anybody who wanted a specific reference for the XML syntax. But it’s not strictly necessary and not used internally, so I can just remove it if you think we should.

[annevk]

Yeah, let's remove it then. There's a couple of sections that can be referenced with exposed IDs.

[sideshowbarker]

id="the-xml-syntax"

Yeah, let's remove it then. There's a couple of sections that can be referenced with exposed IDs.

OK, removed

[sideshowbarker]

I think we may want to be more careful about preserving the auto-generated IDs, however.

Yeah I shouldn’t have changed those to begin with. But I think we got them all reverted in review.

And changing the split-filename has a lot of consequences; either we need to create a redirect, or we should just leave it as-is as a historical note.

Yeah, undid that as well

[annevk]

It's not clear whether these nits are worth fixing, but I'm not sure why we should change the tone from the original as well.

[annevk]

Should this not be "the XML syntax"? This happens here and a couple times below where what used to say XHTML syntax is now just XML.

[sideshowbarker]

Should this not be "the XML syntax"? This happens here and a couple times below where what used to say XHTML syntax is now just XML.

Yup, so changed

[annevk]

For instance, here.

[sideshowbarker]

got this one

[annevk]

And here. Should be "in the HTML and XML syntaxes" I think?

[sideshowbarker]

got it and the rest too

[annevk]

And here.

[annevk]

And here.

Happy with this when Anne's nits are fixed

[zcorpan]

Oh, can you re-wrap to 100 cols also?

[sideshowbarker]

Oh, can you re-wrap to 100 cols also?

yup, will do right now

[annevk]

Ah, so if we keep this as "The XML syntax", and use <span>the XML syntax</span> above, it would be all consistent again. So I think we want to do that too.

[sideshowbarker]

+  <h2 split-filename="xhtml"><dfn id="xhtml">XML</dfn></h2>

Yup, so changed

[annevk]

<span>the XML syntax</span>.

[sideshowbarker]

got it

[annevk]

<span>the XML syntax</span>

[sideshowbarker]

got it

[annevk]

"HTML and XML syntaxes"

[annevk]

<span>the XML syntax</span>

[annevk]

<span data-x="the XML syntax">XML syntax</span> (no need to change this from the original either)

[annevk]

<span>the XML syntax</span>

[annevk]

data-x="the XML syntax"

[annevk]

<span>the XML syntax</span>

[annevk]

I think we should reinstate the "writing-xhtml-documents" ID and subsection (and link it from here).

[sideshowbarker]

I think we should reinstate the "writing-xhtml-documents" ID and subsection (and link it from here).

OK restored the link and restored the heading as:

<h3 id="writing-xhtml-documents">Writing documents in the XML syntax</h3>

[annevk]

data-x="the XML syntax"

[annevk]

not supported there*

[annevk]

data-x="the XML syntax"

[annevk]

Many nits left relative to the original text and a couple of referencing errors as far as I can tell.

[annevk]

I don't see a reason to remove this note or the "Writing XML documents" section following it.

[sideshowbarker]

-  <p class="note">This section only describes the rules for XML resources. Rules for
-  <code>text/html</code> resources are discussed in the section above entitled "<span>The HTML
-  syntax</span>".</p>

I don't see a reason to remove this note or the "Writing XML documents" section following it.

OK—restored both

[annevk]

LGTM, but maybe someone should give it another pass with fresh eyes.

[sideshowbarker]

LGTM, but maybe someone should give it another pass with fresh eyes.

To make that easier, I went ahead and squashed the commits so there’s only one diff to look at.

[zcorpan]

The span needs to wrap the "the" as well to xref correctly. (We need to make wattsi fail for this...)

[annevk]

Do we have a Wattsi bug?

[sideshowbarker]

The span needs to wrap the "the" as well to xref correctly. (We need to make wattsi fail for this...)

oofs, thanks for catching that

[zcorpan]

whatwg/wattsi#33

[zcorpan]

Why is this no longer necessary? "XML documents" here is the DOM concept, and some document conformance differences are stated in terms of that (e.g. noscript). But it might not be clear how that concept applies to a conformance checker without this paragraph.

[sideshowbarker]

-  <p>For the purposes of conformance checkers, if a resource is determined to be in <span>the XHTML
-  syntax</span>, then it is an <span data-x="XML documents">XML document</span>.</p>

Why is this no longer necessary?

I agree it’s necessary now after the round “XML”->“the XML syntax” review changes, so I’ve restored it.

Initially when I had replaced “the XHTML syntax” with just “XML”, this would have become:

For the purposes of conformance checkers, if a resource is determined to be XML, then it is an XML document.

…which didn’t seem to expressing anything implementable…

[annevk]

This is another subtle change. The ID used to be on the <dfn>. I think that distinction is important for Wattsi.

[annevk]

Why not put the "the" inside the span and omit data-x? Same for the note below.

[annevk]

s/in there/there/

[annevk]

I'll push a fix for these remaining nits.

[annevk]

\o/

[sideshowbarker]

w00t

@domenic @annevk @zcorpan thanks for your patience—never meant for this one to consume as much of our time as it ending up taking, but I really think this change was due and I’m glad it got reviewed carefully and worded carefully (especially compared to my initial slash-and-burn attempt)