The intent of this success criteria is to help people better recognize and understand the intention of form inputs by attaching additional information (metadata) to the identified form inputs. This allows for additional machine-processing for personalization and other automation, such as identifying and applying familiar terms or symbols to the inputs, which are needed for users with cognitive disabilities to be able to use the web.
When a user-agent (browser or Assistive Technology) knows what an input is expecting it can then provide the ability for page customization, such as applying familiar icons or standardized labels next to the input. Additionally, using techniques such as the autocomplete attribute (from HTML) will make completing forms easier for everyone, by reducing the overhead of typing in common information such as address and credit card numbers. This benefits all users, but has a much greater impact on people with cognitive impairments.
The approach of adding metadata to indicate the purpose of elements is intended to be compatible with future work on personalization. Work done to implement this success criteria should continue to work when a wider range of personalization attributes are available in future. Although autocomplete provides a very limited scope for personalization, the mechanism for future work is similar which can be seen in the Personalization Semantics Content Module.
This approach will initially seem similar to adding role information (as required by 4.2.1 @@@ link) but actually provides higher level information so the user can understand the intent or purpose of the input. For example, that a field is intended for your name, it is not just a text field.
In the future a more robust set of personalization abilities should be available, such as this personalization demo provides. In this demo, a user can load a set of preferred symbols that are appropriate for them. These symbols can help a people comprehend intent via a toolbar or browser extension which overlays the symbols onto the page. When the autocomplete attribute is used, browser's and browser extensions can also populate form fields on command (or automatically) so the user does not have to remember or transcribe the information.
Common ways to meet this success criteria include:
Providing the autocomplete attribute on suitable inputs - these techniques work on all the specified fields.
The list of values that should be used are available in the HTML5 specification: autocomplete values from HTML5.2.
Following the success criterion benefits users with various cognitive disabilities including people with language and memory related disabilities, and disabilities that affects executive function and decision making. (@@@ link to personas?)