Fixed comment about Graph limitations

Author: darrelmiller

graph/patterns/navigation-property.md

@@ -16,7 +16,7 @@ The use of foreign key properties to describe related resources is a weakly type
 ## Solution
 --------
 
-Navigation properties are an [OData convention](https://docs.microsoft.com/en-us/odata/webapi/model-builder-untyped#navigation-property) that allows an API designer to describe a special kind of property in a model that references an related entity. In the HTTP API this property name translates to a path segment that can be appended to the URL of the primary resource in order to access a representation of the related resource. This prevents the client from needing to know any additional information on how to construct the URL to the related resource and the client does not need to retrieve the primary resource if it is only interested in the related resource.  It is the responsibility of the API implementation to determine the Id of the related resource and return the representation of the related entity.
+Navigation properties are an [OData convention](https://docs.microsoft.com/en-us/odata/webapi/model-builder-untyped#navigation-property) defined in the [CSDL Specification](https://docs.oasis-open.org/odata/odata-csdl-xml/v4.01/odata-csdl-xml-v4.01.html#_Toc38530365) that allows an API designer to describe a special kind of property in a model that references an related entity. In the HTTP API this property name translates to a path segment that can be appended to the URL of the primary resource in order to access a representation of the related resource. This prevents the client from needing to know any additional information on how to construct the URL to the related resource and the client does not need to retrieve the primary resource if it is only interested in the related resource.  It is the responsibility of the API implementation to determine the Id of the related resource and return the representation of the related entity.
 
 e.g. /user/{userId}/manager  # many-to-one relationship
      /user/{userId}/messages # one-to-many relationship
@@ -26,7 +26,7 @@ Additionally, using the OData Expand query parameter, related entities can be tr
 ## Issues and Considerations
 -------------------------
 
-In the current Microsoft Graph implementation, support for navigation properties is limited to entities within the same backend service or the user entity.  
+In the current Microsoft Graph implementation, there are some limitations on the use of navigation properties that cross between backend services. These limitations are being eliminated over time, but it will be necessary to ensure support for any particular scenario.  
 
 Navigation properties defined within an entity are not returned when retreiving the representation of an entity unless explicity desired by a service.