XHTML™ 1.1 - Module-based XHTML - W3C Recommendation.pdf

# XHTML™ 1.1 - Module-based XHTML - Second Edition (W3C Recommendation)

## Abstract
This W3C recommendation defines an XHTML document type based on the module framework and modules outlined in XHTML Modularization. It aims to serve as a foundation for future extended XHTML document types, providing a clean separation from deprecated HTML 4 functionality found in XHTML 1.0. This version is similar to XHTML 1.0 Strict but built using XHTML Modules, excluding certain facilities available in other XHTML Family document types (accessible through defined modules).

## Status
- Publication Date: 23 November 2010
- Latest Version: [XHTML 1.1](http://www.w3.org/TR/xhtml11)
- Previous Version: [XHTML 1.0](http://www.w3.org/TR/2010/REC-xhtml11-20100716)
- Supersedes: Previous XHTML 1.1 edition
- Compliance: Stable, reference material, citable

## Document Type Overview
This document type is designed for broad portability across client devices and applicable to most Internet content. It removes support for deprecated elements and attributes from HTML 4, focusing on structural functionality better handled via style sheets or client defaults.

## Key Changes from XHTML 1.0 Strict
- Module-based Structure: Adopts a modular framework for defining document types.
- Removed Functionality: Excludes non-essential presentation elements and attributes.
- XML Schema Implementation: Includes an XML Schema definition for improved validation.
- lang Attribute Integration: Enhances compatibility with User Agents and Assistive Technologies.

## Conformance Definition (2.1)
### Strictly Conforming Documents (2.1.1)
Documents that meet all requirements of this specification are strictly conforming.

### User Agent Conformance (2.2)
User agents must support the features defined in this document type to be considered conforming.

## The XHTML 1.1 Document Type (Section 3)
This section provides a detailed definition of the XHTML 1.1 document type, including:
- SGML Open Catalog Entry (C.1)
- Driver for XHTML 1.1 (C.2)
- Customizations (C.3)

## Technical Specifications (Sections C-D)
- XML Schema Definition (D): Includes driver, modules, and customizations.
- Ruby Implementation: Provides an alternative implementation using Ruby.

## Acknowledgements (E)
Acknowledges contributors and efforts leading to this recommendation.