The Content Accessibility Guidelines,

We start with a necessary consideration: the 'accessibility is not just the disabled, but all users of the Web, as anyone should be put in a position to benefit from services and content on the Internet.

The issues that the guidelines on the 'accessibility dealt with have fact both disability permanent temporary physical / sensory and cognitive (partially sighted, dyslexic) as those of people without disabilities.

Often it is the latter to meet architectural and programmatic barriers because they do not have recent software, do not speak certain languages ​​or do not have a sufficiently high culture to understand specialized texts. In underestimate the environmental and cultural context in which you work, you underestimate the problem, that is, rather, of great social impact, so that for years is at the core of the W3C. The international body has, in fact, already released two versions of the standards on accessibility, WCAG 1.0 and the latest 2.0.

The guidelines of the W3C

Far from being considered obsolete, the WCAG 1.0, thanks to its modular design is also suitable for the current Web scenario, despite being released in 1999. consists of 14 guidelines, each subdivided into further control points (checkpoints) - 65 in all - each with a priority level, 1 to 3, indicated by the letters A, AA and AAA.

Not to get lost in the detail of each of the 14 guidelines and related sub, there will be more useful to divide themselves into two groups, those from 1 to 11 and those 12 to 14, to which we will match the two main methods of work :

• ensure a pleasant transformation (graceful transformation) of content to be displayed to everyone. They, therefore, refer to the physical perception of the user;
• make content understandable and navigable, and therefore intellectually accessible to everyone.

Working method of the first part concrete actions such as:

• separate structure from the layout of the site or document;
• always provide text equivalents for pictures, images, video;
• create accessible documents, without a specific hardware;
• create documents with equivalent specifications for permanent disability (for example, visually impaired.)

The second method of work are part of actions such as:

• by providing a clear navigation structure;
• write clearly, in language free from unnecessary technicalities;
• to provide tools to navigate the site (bread crumbs, site maps);
• add tools for quick navigation by experienced users.

The WCAG 2.0 relies heavily on version 1.0, which represents an extension, allowing a more abstract and a detailed analysis of four fundamental principles: perceivable, usable, understandable, robust. Among them there is no hierarchical relationship, but we regard them with equal theoretical and practical impact.

It 'very important, however, dwell on the main novelties introduced by version 2.0 compared to 1.0, a new decree that ease of use and immediacy, and fill the gaps of the previous standard.

Crossing the basics with some significant changes, we get the following matrix:

• Perceptible: the user should be able to access the information regardless of their psycho-physical state. The information should not be entrusted exclusively to elements such as colors, positions, fonts, shapes. The same should not be decisive in allowing to perform a certain action.
• Usage: The user must have complete control over the interface. Any action must be reversible, the elimination of the timing for completing the actions, because the reaction times differ greatly from person to person, there must be a simple procedure for re-authentication, without any loss of data previously entered. Errors must be clearly marked and must be given the opportunity to correct. They should therefore be cryptic and written by "experts" (eg, such as: "System error 153D").
• Understandable: the user must be able to understand the workings of the interface and the information contained therein. More attention therefore, the introduction of sound, video, abbreviations, annoying for your understanding. Provide text alternatives (text next to high-level summaries of semantics more easily). Define the language used in HTML, not to run into screen readers - for example, a speech synthesizer - the disastrous performance.
• Robust: the user must be able to access the content by whatever hardware or software used. Particular attention must be paid to interoperability with assistive technologies, providing for the future compatibility or portability.

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