HTML and CSS Reference
User Input and Form Requirements
Form controls and links must be provided using (X)HTML elements rather than other technologies such as Flash.
Text inputs of forms must have a title attribute that can be used for providing context-sensitive help.
An accessible name must be applied for labeling Flash form controls. Flash buttons must always have an
accessible label that describes the purpose of the link. Flash image buttons must have accessible names that provide
information about the function of the buttons but do not describe the images in general.
The label property must be set for the Button , CheckBox , and RadioButton Flash form components explicitly. As
a result, the label text appears next to the component and becomes available for assistive technology.
Groups of form controls must have a description provided by the legend element and must be grouped with
A button must be applied along with select elements to perform an action. The option elements must be
grouped with optgroup within select elements.
To keep proportions, textual form elements such as input boxes and buttons should be resized when the text size
has significantly changed in the browser.
Beyond enumerated options, forms sometimes allow user-defined values (typically with the text other, please
specify ) for which text descriptions must be provided.
Text instructions must be added to the beginning of forms and fieldsets that clearly indicate the required input.
Text input elements may have a spell checker. Required fields must be clearly indicated, for example with an asterisk
( * ) character. The user must be informed through a text description if the input is a prohibited value, falls outside the
allowed limits, or is provided in a nonsupported format.
When using technologies that support Accessible Rich Internet Applications (WAI-ARIA), the allowed range of
entry fields should be identified with the aria-valuemin and aria-valuemax properties. User agents typically do not
permit users to enter values outside the specified range and generate a validation error if users do so.
Expected data formats presented with examples minimize the probability of incorrect or insufficient user input.
The same holds for review and correction options offered before form submitting. A mechanism should be provided
for web applications so that users can recover information deleted by mistake.
Multipart forms must provide a checkbox on the first page that gives users more time if they need it or completely
avoids session time limits.
User input should be validated by means of client-side scripting. If errors are found, an alert dialog must be used
to inform the user. Error messages can also be added via the DOM. Additionally, a mechanism should be provided
that helps users find the location of input errors. If the information supplied by the user is not adequate and cannot be
accepted, correct text should be suggested (if available).
If a Captcha is used on a form, alternate text must be added that describes the purpose of the test such as “the test
determines whether or not the user is human”. There should be an option to refresh the Captcha, i.e., generate another
distorted image if the user cannot read the first one.
A checkbox provided in addition to Submit buttons encourages users to review their input before submitting. If
confirmation is required to continue a selected action, form submission problems can be minimized or eliminated.
After submission, a stated time period should be provided when the order/request can be updated or canceled by the
user. A success feedback should always be provided when data is submitted successfully.
The aria-describedby WAI-ARIA property can be applied to attach descriptive information to one or more
elements. Form controls must be associated with text labels by the label element. When the label element cannot be
used, the title attribute must be applied. Labels must be positioned immediately before the field (with text direction
taken into account) except the labels of radio buttons and checkboxes that are positioned after the field. Form fields
and the buttons that clearly indicate their purpose must be adjacent.