anchor.diff:  `Selector` field.
   +
   Internal OpenShift services use the `Selector` field to associate pods with
  -services via labels. A system component called `EndpointsController`
  -synchronizes the endpoints for services that specify selectors with the pods
  -that match the selector. The service proxy and OpenShift router load-balance
  -requests to the service amongst the service's endpoints.
  -+
  -Services that represent an external resource do not require pods to be
  -associated with an external service. For external services, leave the `Selector`
  -field unset. This represents the external service, making the
  -`EndpointsController` ignore the service and allows you to specify endpoints
  -manually:
  +services via labels. The `EndpointsController` system component synchronizes the
  +endpoints for services that specify selectors with the pods that match the
  +selector. The service proxy and OpenShift router load-balance requests to the
  +service amongst the service's endpoints.
  ++
  +Services that represent an external resource do not require associated pods.
  +Instead, leave the `Selector` field unset. This represents the external service,
  +making the `EndpointsController` ignore the service and allows you to specify
  +endpoints manually:
   +
   ====
   
  
positive.code: 
  *External SaaS Provider Environment Variables*
  
  Like when using an internal service, your application is injected with
  environment variables for the service and the additional environment variables
  with the credentials described in the above steps. In the above example, the
  container receives the following environment variables:
  
negative.code: ====
  
  . Next, create endpoints for the service containing the information about where
  to send traffic directed to the service proxy and the router:
  +
  ====
  
  