Supported Standards

HTML HTML Living Standard Most parts
Atom Atom 1.0 RFC
Atom Threading 1.0 RFC
XML 1.0 Fourth Edition Tentative
1.1 Second Edition Tentative
XML Namespaces 1.0 Second Edition Tentative
1.1 First Edition Tentative
Cache Manifest HTML Living Standard
WebIDL Editor's Draft 1.96 Out of date!
HTTP Tentative (no validation)


The current implementation assumes that there are following requirements:


Conformance checking as per the Web Applications 1.0 (including HTML5) specification and the manakai's Conformance Checking Guideline for Obsolete HTML Elements and Attributes is supported, except for a few newer features such as Microdata and device (those features will be implemented later).

The cache manifest syntax is also supported.


Atom 1.0 and Atom Threading 1.0 are supported.

However, conformance to some SHOULD-level requirements, as well as some informational guidelines, are currently not checked. In addition, whether an email-address or a Base64 encoding is correct or not is not checked either.

Use of XML digital signature and encryption is not supported.

The current implementation assumes that there are following requirements:

CSS and related technologies

The following specifications are implemented:

Most of CSS 2.1 ( Candidate Recommendation) is implemented.

Most of CSS Color Module Level 3 ( Last Call Working Draft) is implemented.

Pseudo-classes :past and :future from Selectors4 and WebVTT and pseudo-element ::cue/::cue(selector) from WebVTT are also implemented.

Since the CSS 2.1 specification is sometimes ambigious or disagree with browsers, our implementation is tend to copy what browsers do unless there is strong resaon to do different thing.

In addition, the current implementation assumes that there are following requirements:


The WebVTT language specified by the WebVTT Living Standard (as of 26 April 2012) is implemented.

Regular expressions

Regular expression defined in ECMAScript Third Edition Section 15.10.1 is implemented, with the addition of the support for obsolete octal escape notation commonly supported by Web browsers.

To identify ECMAScript regular expressions, the Internet Media Type text/x-regexp-js is used.

Language tags

RFC 5646 (language tags) and RFC 4647 (language ranges) are supported. In addition, historical revisions, i.e. RFC 4646, RFC 3066, and RFC 1766 are also supported as well.

Extension 'u' (RFC 6067 / CLDR / UTS #35) is supported.

For the purpose of interpretation of these specification, statements of fact describing the nature of the language tags, the constraints expressed using the ABNF grammer, and list of available values, are considered as MUST-level requirements for the purpose of conformance checking.


WebIDL Editor's Draft revision 1.96 () is implemented.