Difference between revisions of "FAQ"
(→What is the namespace declaration?)
|Line 182:||Line 182:|
In HTML, the <code>xmlns</code> attribute is currently
In HTML, the <code>xmlns</code> attribute is currently allowed on element, only if it has the value “<code>http://www.w3.org/1999/xhtml</code>“. It doesn’t do anything at all, it is merely allowed to ease migration from XHTML 1.0. It is not actually a namespace declaration in HTML, because HTML doesn’t yet support namespaces. See the question [[FAQ#Will_there_be_support_for_namespaces_in_HTML.3F|will there be support for namespaces in HTML]].
=== Will there be support for namespaces in HTML? ===
=== Will there be support for namespaces in HTML? ===
Revision as of 16:06, 5 August 2008
- 1 The WHATWG
- 2 The WHATWG Process
- 3 HTML5
- 4 Syntax issues
- 4.1 Will (X)HTML 5 finally put an end the XHTML as text/html debate?
- 4.2 What will the DOCTYPE be?
- 4.3 If there is no DTD, how can I validate my page?
- 4.4 What is an HTML Serialisation?
- 4.5 What is an XML (or XHTML) Serialisation?
- 4.6 What MIME type does HTML5 use?
- 4.7 Should I close empty elements with /> or >?
- 4.8 If I’m careful with the syntax I use in my HTML document, can I process it with an XML parser?
- 4.9 What is the namespace declaration?
- 4.10 Will there be support for namespaces in HTML?
- 4.11 How do I specify the character encoding?
- 4.12 What are the differences between HTML and XHTML?
- 4.13 Why does HTML5 legitimise tag soup?
- 5 Feature proposals
- 6 WHATWG and the W3C HTML WG
What is the WHATWG?
The WHATWG is a growing community of people interested in evolving the Web. It focuses primarily on the development of HTML and APIs needed for Web applications.
The WHATWG was founded by individuals of Apple, the Mozilla Foundation, and Opera Software in 2004, after a W3C workshop. Apple, Mozilla and Opera were becoming increasingly concerned about the W3C’s direction with XHTML, lack of interest in HTML and apparent disregard for the needs of real-world authors. So, in response, these organisations set out with a mission to address these concerns and the Web Hypertext Application Technology Working Group was born.
What does the acronym WHATWG stand for?
It stands for "Web Hypertext Application Technology Working Group".
What is the WHATWG working on?
The WHATWG is working on HTML 5 (see below). In the past it has worked on Web Forms 2.0 and Web Controls 1.0 as well. Web Forms 2.0 (see below) has reached a stable stage and we're awaiting implementation experience. Web Controls 1.0 has been abandoned for now, awaiting what XBL 2.0 will bring us.
How can I get involved?
There are lots of ways you can get involved, take a look and see What you can do!
Is participation free?
Yes, everyone can contribute. There are no memberships fees involved, it's an open process. You may easily subscribe to the WHATWG mailing lists. You may also join the the W3C's new HTMLWG by going through the slightly longer application process.
The WHATWG Process
How does the WHATWG work?
People send e-mail to the mailing list. The editor then reads that feedback and, taking it into account along with research, studies, and feedback from many other sources (blogs, forums, IRC, etc) makes language design decisions intended to address everyone's needs as well as possible while keeping the language consistent.
This continues, with people sending more feedback, until nobody is able to convince the editor to change the spec any more (e.g. because two people want opposite things, and the editor has considered all the information available and decided that one of the two proposals is the better one).
This is not a consensus-based approach -- there's no guarantee that everyone will be happy! There is also no voting.
There is a small oversight committee (known as the "WHATWG members", see the charter) who have the authority to override or replace the editor if he starts making bad decisions.
Currently the editor is Ian Hickson.
How should browser developers interact with the WHATWG?
Feedback on a feature should be sent to email@example.com (but you have to join the mailing list first), or firstname.lastname@example.org. All feedback will receive a reply in due course.
If you want feedback to be dealt with faster than "eventually", e.g. because you are about to work on that feature and need the spec to be updated to take into account all previous feedback, let the editor know by either e-mailing him (email@example.com), or contacting him on IRC (Hixie on Freenode). Requests for priority feedback handling are handled confidentially so other browser vendors won't know that you are working on that feature.
Questions and requests for clarifications should be asked either on the mailing list or on IRC, in the #whatwg channel on Freenode.
Note: Browser developers are also referred to as UA developers or implementors. UA stands for User Agent and is basically the technical term for "browser".
When will HTML 5 be finished?
"Finished" is a big deal... You'll be able to use HTML5 long before then. See When will we be able to start using these new features?
It is estimated by the editor that HTML5 will reach the W3C Candidate Recommendation stage during 2012. That doesn't mean you can't start using it yet, though. Different parts of the specification are at different maturity levels. Some sections are already relatively stable and there are implementations that are already quite close to completion, and those features can be used today (e.g. <canvas>). But other sections are still being actively worked on and changed regularly, or not even written yet.
You can see annotations in the margins showing the estimated stability of each section.
The possible states are:
- Idea; yet to be specified -- the section is a placeholder.
- First draft -- An early stage.
- Working draft -- An early stage, but more mature than just "first draft".
- Last call for comments -- The section is nearly done, but there may be feedback still to be processed. Send feedback sooner rather than later, or it might be too late.
- Awaiting implementation feedback -- The section is basically done, but might change in response to feedback from implementors. Major changes are unlikely past this point unless it is found that the feature, as specified, really doesn't work well.
- Implemented and widely deployed -- the feature is specified and complete. Once a section is interoperably implemented, it’s quite stable and unlikely to change significantly. Any changes to such a section would most likely only be editorial in nature, particularly if the feature is already in widespread use.
There are also two special states:
- Being edited right now -- the section is in high flux and is actively being edited. Contact Hixie on IRC if you have immediate feedback.
- Being considered for removal -- for one reason or another, the section is being considered for removal. Send feedback soon to help with the decision.
The point to all this is that you shouldn’t place too much weight on the status of the specification as a whole. You need to consider the stability and maturity level of each section individually.
It is estimated, again by the editor, that HTML5 will reach a W3C recommendation in the year 2022 or later. This will be approximately 18-20 years of development, since beginning in mid-2004. That's actually not that crazy, though. Work on HTML4 started in the mid 90s, and HTML4 still, more than ten years later, hasn't reached the level that we want to reach with HTML5. There is no real test suite, there are many parts of the spec that are lacking real implementations, there are big parts that aren't interoperable, and the spec has hundreds if not thousands of known errors that haven't been fixed. When HTML4 came out, REC meant something much less exciting than it does now.
For a spec to become a REC today, it requires two 100% complete and fully interoperable implementations, which is proven by each successfully passing literally thousands of test cases (20,000 tests for the whole spec would probably be a conservative estimate). When you consider how long it takes to write that many test cases and how long it takes to implement each feature, you’ll begin to understand why the time frame seems so long.
(In the interests of full disclosure, the W3C's official line is that the HTML5 spec will be complete, with interoperable implementations, in late 2010. However, as of December 2007 the W3C had already missed the first milestone on that same timetable, First Public Working Draft, by 6 months, with no reason to believe publication would come soon. You can make your own judgements regarding the W3C timetable's credibility.)
Is there a process for removing bad ideas from the spec?
There are several processes by which we trim weeds from the specifications.
- On a regular basis, especially around explicit call-for-comments, we go through every section and mark areas as being considered for removal. This happened early in 2008 with the data templates, repetition blocks, and DFN-element cross references, for example. If no feedback is received to give us strong reasons to keep such features, then they eventually are removed altogether.
- Anyone can ask for a feature to be removed; such feedback is considered like all other feedback and is based on the merits of the arguments put forward.
- If browsers don't widely implement a feature, or if authors don't use a feature, or if the uses of the feature are inconsequential of fundamentally wrong or damaging, then, after due consideration, features will be removed.
Removing features is a critical part of spec development.
Is there a process for adding new features to the spec?
The process is rather informal, but basically boils down to this:
- Research the use cases and requirements by discussing the issue with authors and implementors. Read the responses. Listen to the feedback. Consider whether your ideas are good solutions to the use cases and requirements put forward. Discussions here should be done in public, e.g. on an archived public mailing list or documented in blogs.
- Get implementors to commit to implementing the feature. If you can't get several implementors to implement the feature, then get at least one user agent to implement it experimentally. Experimental implementations should be publicly available.
- Bring the experimental implementations to the attention of the spec's editor. Document the experience found from any implementations, the use cases and requirements that were found in the first step, the data that the design was based on.
- Participate in the subsequent design discussions, considering all the proposals carefully. Typically at this step the original design gets thrown out and a significantly better design is developed, informed by the previous research, new research, and implementation and author experience with experimental implementations. Sometimes, the idea is abandoned at this stage.
If the idea survives the above design process, the spec will be eventually updated to reflect the new design. Implementations will then be updated to reflect the new design (if they aren't, that indicates the new design is not good, and it will be reworked or removed). The spec will be updated to fix the many problems discovered by authors and implementors, over a period of several years, as more authors and implementors are exposed to the design. Eventually, a number of provably interoperable implementations are deployed. At this point development of the feature is somewhat frozen.
Writing a comprehensive test suite is also an important step, which should start a bit before implementations start being written to the spec. (Test suites usually find as many problems with implementations as they do with the spec; they aren't just for finding browser bugs.) We don't yet have a good story with respect to test suites, sadly. If you want to help us out, let the mailing list know! Be aware, though, it's a lot of work.
What is HTML 5?
HTML 5 is the main focus of the WHATWG community and also that of the (new) W3C HTML Working Group. HTML 5 is a new version of HTML 4.01 and XHTML 1.0 addressing many of the issues of those specifications while at the same time enhancing (X)HTML to more adequately address Web applications. Besides defining a markup language that can be written in both HTML (HTML5) and XML (XHTML5) it also defines many APIs that form the basis of the Web architecture. These APIs are known to some as "DOM Level 0" and have never been documented. Yet they are extremely important for browser vendors to support existing Web content and for authors to be able to build Web applications.
What is Web Forms 2.0?
Web Forms 2.0 is an update to the forms chapters of HTML 4.01 and XHTML 1.0. The specification is informally declared feature complete and the WHATWG is awaiting implementation experience. This specification will in due course be folded into the HTML 5 specification when HTML 5 reaches a more stable state.
How can I keep track of changes to the spec?
The specification is available in the subversion repository. You may use any svn client to check out the latest version and use your clients diff tools in order compare revisions and see what has been changed. You may also use the online (X)HTML5 Tracker Tool. The tool provides an online interface for selecting and comparing revisions of the spec.
When will we be able to start using these new features?
As soon as browsers begin to support them. You do not need to wait till HTML5 becomes a recommendation, because that can’t happen until after the implementations are completely finished.
For example, the <canvas> feature is already widely implemented.
The specification has annotations in the margins showing what browsers implement each section.
What about Microsoft and Internet Explorer?
Microsoft has already started implementing parts of HTML5 in IE8.
Will (X)HTML 5 finally put an end the XHTML as
Yes. Unlike HTML 4.01 and XHTML 1.0, the choice of HTML or XHTML is solely dependent upon the choice of MIME type, rather than the DOCTYPE. See HTML vs. XHTML
What will the DOCTYPE be?
<!doctype html>. The only reason there is one for HTML is to trigger standards mode in browsers.
In XHTML: no DOCTYPE. You may include one if you wish, though this is not recommended as they are only relevant when using a validating parser which web browsers do not have.
If there is no DTD, how can I validate my page?
With an HTML 5 validator.
What is an HTML Serialisation?
The HTML serialisation refers to the syntax of an HTML document defined in HTML5. The syntax is inspired by the SGML syntax from earlier versions of HTML, but it is defined to be more compatible with the way browsers actually handle HTML in reality.
Any document whose MIME type is determined to be
text/html is considered to be an HTML serialisation, even if the author has tried to use XML syntax.
What is an XML (or XHTML) Serialisation?
The XML Serialization refers to the syntax defined by XML 1.0 and Namespaces in XML 1.0. A resource that has an XML MIME type, such as
application/xml, is an XML document and if it uses elements in the HTML namespace, it contains XHTML. If the root element is “html” in the HTML namespace, the document is referred to as an XHTML document.
What MIME type does HTML5 use?
The HTML serialisation must be served using the
text/html MIME type.
The XHTML serialisation must be served using an XML MIME type, such as
application/xml. Unlike XHTML 1.0, XHTML 5 must not be served as
Using the incorrect MIME type (
text/html) for XHTML will cause the document to be parsed according to parsing requirements for HTML. In other words, it will be treated as tag soup. Ensuring the use of an XML MIME type is the only way to ensure that browsers handle the document as XML.
Should I close empty elements with
Void elements in HTML (the new name for empty elements) do not require a trailing slash. e.g. Instead of writing
<br />, you only need to write
<br>. This applies to all void elements, including
However, due to the widespread attempts to use XHTML 1.0, there are a significant number of pages using the trailing slash. Because of this, the syntax has been permitted (though it is not recommended) in order to ease migration from XHTML 1.0 to HTML5.
It is important to realise that this syntax serves no purpose in HTML, it is just ignored by browsers. Despite the fact that it is based upon the XML syntax, it does not mean that HTML documents can be parsed with XML tools. HTML and XHTML are separate serialisations and they each must be processed using tools designed to handle each format.
If I’m careful with the syntax I use in my HTML document, can I process it with an XML parser?
No, HTML and XML have many significant differences, particularly parsing requirements, and you cannot process one using tools designed for the other. However, since HTML5 is defined in terms of the DOM, in most cases there are both HTML and XHTML serialisations available that can represent the same document. There are, however, a few differences explained later that make it impossible to represent some HTML documents accurately as XHTML and vice versa.
If you wish to process an HTML document as XHTML, it requires that you and convert it into XHTML first; and vice versa for processing XHTML as HTML.
What is the namespace declaration?
In XHTML, you are required to specify the namespace. (need to find a simple explanation for what namespaces are for)
In HTML, the
xmlns attribute is currently allowed on any HTML element, but only if it has the value “
http://www.w3.org/1999/xhtml“. It doesn’t do anything at all, it is merely allowed to ease migration from XHTML 1.0. It is not actually a namespace declaration in HTML, because HTML doesn’t yet support namespaces. See the question will there be support for namespaces in HTML.
Will there be support for namespaces in HTML?
HTML 5 is being defined in terms of the DOM and all HTML elements will exist in the HTML namespace:
http://www.w3.org/1999/xhtml. However, unlike the XHTML serialisation, there is no real namespace syntax available in the HTML serialisation (see previous question). In other words, you do not need to declare the namespace in your HTML markup, like you do in XHTML.
XHTML requires that the namespace to be declared appropriately using the
xmlns attribute. The namespace declaration is unnecessary in HTML because browsers will already know it’s an HTML document based on the MIME type (
How do I specify the character encoding?
For HTML, it is strongly recommended that you specify the encoding using the HTTP
Content-Type header. If you are unable to configure your server to send the correct headers, then you may use the
meta element. The
meta element used for this purpose must occur as the first element in the head (even before the
title), and within the first 512 bytes of the file.
Note that this
meta element is different from HTML 4, though it is compatible with many browsers because of the way encoding detection has been implemented.
In XHTML, XML rules for determining the character encoding apply. You may use either the HTTP
Content-Type header or the XML declaration to specify the encoding.
<?xml version="1.0" encoding="UTF-8"?>
Otherwise, you must use the default of
UTF-16. It is recommended that you use
What are the differences between HTML and XHTML?
See the list of differences between HTML and XHTML in the wiki.
Why does HTML5 legitimise tag soup?
Actually it doesn’t. This is a misconception that comes from the confusion between conformance requirements for documents, and the requirements for user agents.
Due to the fundamental design principle of supporting existing content, the spec must define how to handle all HTML, regardless of whether documents are conforming or not. Therefore, the spec defines (or will define) precisely how to handle and recover from erroneous markup, much of which would be considered tag soup.
For example, the spec defines algorithms for dealing with syntax errors such as incorrectly nested tags, which will ensure that a well structured DOM tree can be produced.
Defining that is essential for one day achieving interoperability between browsers and reducing the dependence upon reverse engineering each other.
However, the conformance requirements for authors are defined separately from the processing requirements. Just because browsers are required to handle erroneous content, it does not make such markup conforming.
For example, user agents will be required to support the marquee element, but authors must not use the marquee element in conforming documents.
It is important to make the distinction between the rules that apply to user agents and the rules that apply to authors for produce conforming documents. They are completely orthogonal.
HTML5 should support
href on any element!
The spec allows <a> to contain blocks. It doesn't support putting href="" on any element, though.
href on any element has several problems associated with it that make it difficult to support in HTML5. The main reason this isn't in HTML5 is that browser vendors have reported that implementing it would be extremely complex. Browser vendors get to decide what they implement, and there's no point us telling them to do something they aren't going to do. In addition:
- It isn’t backwards compatible with existing browsers.
- It adds no new functionality that can’t already be achieved using the
aelement and a little script.
- It doesn’t make sense for all elements, such as interactive elements like
button, where the use of href would interfere with their normal function.
The only advantage it seems to add is that it reduces typing for authors in some cases, but that is not a strong enough reason to support it in light of the other reasons.
Wrapping <a> elements around blocks solves most use cases. It doesn't handle making rows in tables into links, though; for those just do something like this instead:
<tr onclick="location = this.getElementsByTagName('a')"> ... </tr>
HTML5 should support a way for anyone to invent new elements!
There are actually quite a number of ways for people to invent their own extensions to HTML:
- Authors can use the class attribute to extend elements, effectively creating their own elements, while using the most applicable existing "real" HTML element, so that browsers and other tools that don't know of the extension can still support it somewhat well. This is the tack used by Microformats, for example.
- Authors can include data for scripts to process using the data-*="" attributes. These are guaranteed to never be touched by browsers, and allow scripts to include data on HTML elements that scripts can then look for and process.
- Authors can use the <meta name="" content=""> mechanism to include page-wide metadata. Names should be registered on the wiki's MetaExtensions page.
- Authors can use the rel="" mechanism to annotate links with specific meanings. This is also used by Microformats. Names should be registered on the wiki's RelExtensions page.
- Authors can embed raw data using the <script type=""> mechanism with a custom type, for further handling by a script.
- Authors can create plugins and invoke them using the <embed> element. This is how Flash works.
- Authors can propose new elements and attributes to the working group and, if the wider community agrees that they are worth the effort, they are added to the language. (If an addition is urgent, please let us know when proposing it, and we will try to address it quickly.)
There is currently no mechanism for including non-visible proprietary metadata (i.e. new elements and attributes) intended for use by user agents in HTML documents without discussing the extension with user agent vendors and the wider Web community. This is intentional; we don't want user agents inventing their own proprietary elements and attributes like in the "bad old days" without working with interested parties to make sure their feature is well designed.
We request that people not invent new elements and attributes to add to HTML without first contacting the working group and getting a proposal discussed with interested parties.
WHATWG and the W3C HTML WG
Are there plans to merge the groups?
Not especially. There are people who for a number of reasons are unable to join the W3C group, and there are others who are unable to join the WHATWG group. The editor is in both groups and takes all input into account -- and there are far more places where input on HTML5 is sent than just these two mailing lists (e.g. blogs, firstname.lastname@example.org, forums, direct mail, meetings, etc).
The editor takes feedback from everyone into account and does not look at the source of those arguments for technical arguments.