ISO/IEC 13250-3:2013为主题地图定义了基于XML的交换语法，可用于交换ISO/IEC 13250-2中定义的数据模型实例。它还定义了从交换语法到数据模型的映射。语法是用RELAX-NG模式定义的，通过映射到数据模型可以提供更高的精度，这也有效地定义了语法的解释。

ISO/IEC 13250-3:2013 defines an XML-based interchange syntax for Topic Maps, which can be used to interchange instances of the data model defined in ISO/IEC 13250-2. It also defines a mapping from the interchange syntax to the data model. The syntax is defined with a RELAX-NG schema, and more precision is provided through the mapping to the data model, which effectively also defines the interpretation of the syntax.