aria-multiline
Indicates whether a text box accepts multiple lines of input or only a single line.
Widget attributes are specific to common user interface elements found on GUI systems or in rich internet applications which receive user input and process user actions. These attributes are used to support the widget roles.
Widget attributes might be mapped by a user agent to platform accessibility API state, for access by assistive technologies, or they might be accessed directly from the DOM. User agents MUST provide a way for assistive technologies to be notified when states change, either through DOM attribute change events or platform accessibility API events.
Widget attributes might be mapped by a user agent to platform accessibility API state, for access by assistive technologies, or they might be accessed directly from the DOM. User agents MUST provide a way for assistive technologies to be notified when states change, either through DOM attribute change events or platform accessibility API events.
Description
Indicates whether a text box accepts multiple lines of input or only a single line.
Note: In most user agent implementations, the default behavior of the ENTER or RETURN key is different between the single-line and multi-line text fields in HTML. When user has focus in a single-line <input type="text"> element, the keystroke usually submits the form. When user has focus in a multi-line <textarea> element, the keystroke inserts a line break. The WAI-ARIA textbox role differentiates these types of boxes with the aria-multiline attribute, so authors are advised to be aware of this distinction when designing the field.
Example
Characteristics
Semantic HTML
Reference