This specification provides web content authors a standard approach to support web users with various cognitive and learning disabilities who:

The technology described in this specification is intended to be used to programmatically transform the appearance of typical web content including form controls, icons, and other user interface elements into a rendering incorporating an individual user's preferred AAC symbols. The W3C WAI-Adapt Symbols Registry provides the required mappings between concept values used by content authors and the user's preferred AAC symbol set representation of that concept.

This WAI-Adapt: Symbols Module is a component of the WAI-Adapt series introduced in the WAI-Adapt Explainer document [[adapt]].



This specification module enables authors to add semantic information about content at the element level, in order to facilitate a more familiar and comprehensible interface for the individual user who requires AAC symbols support. Final renderings — generated via helper apps or 3rd-party tools — are ultimately defined by the user's configuration settings.

The goal of the attribute and values described in this specification is to enable personalized communication and web content interaction for the individual user. This specification includes facilities to:

WAI-Adapt is more fully introduced in our WAI-Adapt Explainer [[adapt]].

WAI-Adapt: Symbols Module

WAI-Adapt: Symbols Module is the first part of the WAI-Adapt technical specification, which provides WAI-Adapt and vocabularies that can be used to mark-up web content with additional semantic information, enabling user agents to augment or adapt content to various user-scenarios based on the user’s personalization settings or preferences. The Symbols Module allows authors to enhance web content by providing additional information about the meaning of specific parts of the content. User agents use these semantics to augment or adapt content to the user's preferred symbol set. This helps users with varying needs better understand the content.

Vocabulary Structure and Implementations

The vocabulary in WAI-Adapt: Symbols Module is constructed of properties and their values. Please see our WAI-Adapt Explainer.

The vocabulary implementation included in this module specification is available at our implementations wiki page.


Properties are the main units of WAI-Adapt types supported by the vocabulary. A given property supports a specific type of personalization. That property would only be used once on a given piece of content, but multiple different properties could be used on the same piece of content to address different needs.


Values provide the specific WAI-Adapt information for the property. The possible values for each property are elaborated in the definition of the property in the modules. Some properties require the value to come from a predefined list of possible values, others can accept arbitrary strings, and some may accept multiple values. The attribute value may be one of the following types:

ID reference
Reference to the ID of another element in the same document
ID reference list
A list of one or more ID references.
A numerical value without a fractional component.
Any real numerical value.
Unconstrained value type.
One of a limited set of allowed values.
token list
A list of one or more tokens.
A Uniform Resource Identifier as defined by RFC 3986 [RFC3986] It may reference a separate document, or a content fragment identifier in a separate document, or a content fragment identifier within the same document.

Note that the attributes and values in this specification do not override the semantics exposed in the accessibility tree, but rather augment them. In the case of conflict between an element's semantics and the attribute values, validation algorithms should issue a warning but not an error.

Since implementations have not yet been finalized, any examples in this document are illustrative only, and are provided to help in understanding the concept. All examples will be updated once implementation examples are finalized.

Use Cases and Requirements

The Requirements document for WAI-Adapt describes use cases and requirements which, in turn, are derived from the user scenarios and use cases published in the W3C Note, Making Content Usable for People with Cognitive and Learning Disabilities. This specification module provides one key component to fulfil those requirements related to adapting content to support AAC symbols.


This document uses a number of specific terms related to various cognitive disabilities and related user-needs. Those terms have been defined by the Cognitive and Learning Disabilities Accessibility Task Force. See the COGA Glossary for specific definitions.

This section is normative.

The content of WAI-Adapt Symbols consists of numeric values for the adapt-symbol attribute for any span of text and taken from the W3C WAI-Adapt Registry corresponding to the concept associated with that Registry numeric value. Authors MAY use this attribute in HTML content to enhance the personalizability of the content ad libitum. There is no requirement that all content must be marked with adapt-symbol index values, and there is no minimum.


Privacy and Security Considerations

This specification adds context information about content to the document, and should not affect security.

Although this specification does not expose personal preferences and personal information, third party user agents or proxy server(s) acting upon our semantic information may need to store personal preferences on how to present content to a specific user. It is recommended that any user agent or proxy server implements best practices to protect all personal preferences and personal information.

Any user agent with user settings are recommended to follow best practices to keep user information secure.

The Privacy and Security Considerations of WAI-Adapt: Symbols Module is also discussed at issue #131.

Candidate Recommendation Exit Criteria

The WAI Adapt: Symbols Module specification consists of the symbol attribute that may be added to a page’s HTML at the website’s discretion. A user agent may take suitable rendering decisions based on these attributes.

For the specification to exit Candidate Review status: for the attribute-value in the specification, at least two user agents (or extensions to existing user agents) react to the attribute in an identifiable manner which is suited to the semantics of the attribute.

For clarity, we note:

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