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developer topics and notes. content on this page is subject to change as development updates occur.

other web sites linked from the dev directory on are maintained by other particular organizations or individuals.*


icas.datetime MetaExtensions

please see AAT ICAS proposed specification of 'icas.datetime' meta keywords for HTML(5) on


deployment of HTML.xht

special note: at the time of this revision, it is not yet known what issues if any may concern HTML.xht once the forthcoming HTML5 standards are farther along.

this web site initially used the Dublin Core Metadata Initiative meta tag for format. as HTML5 remains in progress, this web developer elects to consider deployment of a format value of HTML.xht

meta name="DC.Format" content="xht"

as the deployment of HTML.xht is not at present known to be a big topic among many web developers, this web developer will denote HTML.xht in terms of a reverse domain notation metatag:

meta name="com.enhanceability.format" content="HTML.xht"

should xHTML.xht ever need to be distinguished from HTML.xht (in a web context that might include both extensible and legacy content), then that identification of a web format shall remain subject to a future update. in any case, this web developer intends to eventually use a standard format identifier as a means to improve access to formatted content.

this web site deploys the more efficient and more powerful XHTML 1.1 markup, and also makes use of a developer-recognized file extension that consists of a more readily usable 3, rather than a less readily usable 5, characters. some current developments of web standards indicate that these approaches can be regarded as best practices.

these gains in efficiency and standards interoperability however call for the use of modern browsers that can display documents with XHTML and CSS constructs. yet during the deployment of the newer XHTML 1.1 documents with an 'xht' filetype, some issues arose. there is some widespread (though possibly not yet fully integrated by all vendors) support for XHTML 1.1 doctype documents with an 'xht' file extension.

the following development notes for the deployment of HTML.xht (XHTML 1.1 with file extension xht) on the web site are intended to provide some pertinent information concerning HTML.xht compatibility. the following notes do not represent exhaustive nor complete testing of standards compatibility or support. it is however anticipated that remaining undeveloped ('?') support for the 'xht' file extension could be addressed with minor release software patch updates.


why use 'xhtml' or 'xht' rather than 'html' file extension for XHTML 1.1 documents?

although there does not appear to be a widely-used web standard on file extensions, the file extensions xhtml and xht have been recognized by a number of different authors. for additional information about the establishment of the 'xht' file extension for XHTML documents, please refer to the following:

a recent version of a W3C Note on XHTML Media Types provides additional information about a particular methodology for designating an XHTML document. interested readers may also note that a recent version of the W3C markup validator has suppressed a mime type warning (5197) about the use of an 'html' file extension for an XHTML 1.1 document.


comparisons of HTML.xht compatibility

web developers may have good reasons to use a recognized file extension such as xht that is different from a legacy setting. vendor support for the 'xht' file extension is however difficult to compare. one might anticipate that support for the 'xht' file extension could be accommodated with methods similar to those used for the 'xhtml' or 'html' file extensions. these comparisons are subject to developments by vendors and standards developers.

file extension support with XHTML 1.1 doctype

Safari 5.0 (Mac OS X)+++
Opera 9.51 (Mac OS X)+++
Firefox 3.0 (Mac OS X)+++
Internet Explorer 7 (Windows)+?download??download? web server+++ web server+++
W3C markup validator (c8B)warning++
W3C markup validator (c8H)+++
Oxygen 11.2 markup validation+++


**Dreamweaver needed to be reconfigured manually to treat the 'xht' file extension like an HTML document. see the Adobe web site for more information. and a recent update of Dreamwever CS5 still requires a manual configuration of a user extensions file to work with the HTML files with an xht extension. maybe a future update will already include the xht extension as an HTML type of document.

***the 'xhtml' and 'xht' filetypes could be checked for both well-formedness and for xml/doctype validity regardless of whether opened in terms of an xml or an html filetype.

the web server should also be configured to serve XHTML 1.1 documents with 'xhtml' or 'xht' extensions as content-type 'application/xhtml+xml' rather than the 'text/html' content type served for legacy HTML documents (yet note that forthcoming HTML 5 specification is expected to encompass the XML syntax of XHTML 1.1 as one particular syntax). check with W3C for further information.

patching 'xht' for IE7 might be as simple as adding the 'xht' file extension to the list of other HTML filetypes like 'html', 'htm', and 'xhtml'.

why is a HTML.xht useful for web users and developers?

from a web usability standpoint, there are many common user tasks for which a 3 character 'xht' file extension is more readily usable than a 5 character 'xhtml' file extension. users who use a touch type screen rather than a full-sized keyboard, or who paste a URL, can benefit from a more readily usable file name extension such as 'xht'.

XHTML documents do not need to run the larger legacy HTML instruction sets used by legacy HTML and thus can be rendered by modern XHTML browsers more efficiently in comparison to legacy HTML documents. XHTML 1.1 documents are moreover more interoperable with the widely-used XML standards for structuring information.

CSS standards make possible a more efficient presentation of structured content in terms of dedicated style rules.


here are links to some test files for the following XHTML 1.1 doctype documents with various file extensions:

* principal Ronald L Stone is an ardent supporter of Alliance for the Advancement of Technology's educational programs.


top copyright © 2013 UCA and prior, Ronald L Stone, all rights reserved. terms of use. contact. web page updated:
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AD 2013 December 31 Tuesday SMH UT 02:46:04