ANSI/NISO Z39.96-2015

10 Article Authoring Tag Set, version 1.1 • 10.4 Elements

10.4.112 <label> Label (of an Equation, Figure, Reference, etc.)

Number and/or prefix word placed at the beginning of display elements (for example, equation, statement, figure).

Attributes:
@alt Alternative Text
@id Document Internal Identifier
@xml:base Base
@xml:lang Language
Content model:

Text, numbers, or special characters, zero or more