The symbol used to represent a service contract is displayed in Figure 1. Note how REST service contracts have a distinct notation (as explained in the REST Service Capabilities and REST Service Contracts section).
Figure 1 - The chorded circle symbol used to display an Invoice service contract (left) and a variation of this symbol used specifically for REST service contracts (right).
The view provided in Figure 1 is required when modeling services and designing service contracts. When an architectural view of a service is needed, the contract is shown as one artifact wedged among others within the service's implementation, as demonstrated in Figure 2.
Figure 2 - The service contract as part of a service architecture (top) and a variation of the architecture that incorporates a REST service contract (bottom).