This document discusses declaring attributes in XML schemas. Attributes can be declared in schemas to facilitate validating XML documents. Attributes are declared using an attribute element, which can specify the attribute's name, type, allowed values, etc. Attributes can be declared globally to enable reuse across elements. Schemas also allow restricting attribute and element values using simple type definitions and the restriction element. Examples are provided of restricting age to a numeric range and gender to a fixed set of options.