The `<semantics>` element is a MathML 2.0 construct that can be used to associate additional information with a MathML construct. The construct can be used to decorate a MathML expressions with a sequence of one or more `<annotation>` or `<annotation-xml>` elements. Each such element contains a pair of items; the first is a symbol that acts as an attribute or key, and the second is the value associated with the attribute or key. Please refer to the MathML 2.0 documentation, particularly the Section 5.2, Semantic Annotations for more information about these constructs.