The UAF Service Taxonomy: Decomposition (Fit for Purpose) viewpoint enables you to model ServiceSpecfications, their hierarchy (through the ServicePartOfService relationship line), and relationships of ServiceSpecifications to each other (through ServiceInterfaces and Service Connectors).

A complimentary viewpoint is the Sv-Tx Service Taxonomy diagram, where the hierarchy of ServiceSpecifications can be viewed/created as one ServiceSpecification drawn inside of another ServiceSpecification.