ANSI/NISO Z39.96-2015

10 Article Authoring Tag Set, version 1.1 • 10.4 Elements

10.4.11 <alt-text> Alternate Text Name (for a figure, etc.)

Word or phrase used to provide a very short textual name, description, or purpose-statement for a structure such as a graphic or figure.

Attributes:
Content model:

Text, numbers, or special characters