ODATA-1482 (#142)

docs/odata-protocol/odata-protocol.html

@@ -913,7 +913,7 @@ <h2 id="93-server-error-responses"><a name="ServerErrorResponses" href="#ServerE
 <h3 id="931-response-code-501-not-implemented"><a name="ResponseCode501NotImplemented" href="#ResponseCode501NotImplemented">9.3.1 Response Code <code>501 Not Implemented</code></a></h3>
 <p>If the client requests functionality not implemented by the OData Service, the service responds with <code>501 Not Implemented</code> and SHOULD include a response body describing the functionality not implemented.</p>
 <h2 id="94-error-response-body"><a name="ErrorResponseBody" href="#ErrorResponseBody">9.4 Error Response Body</a></h2>
-<p>The representation of an error response body is format-specific. It consists at least of the following information:</p>
+<p>An error response body can be the result of a failure of OData processing or of the underlying infrastructure. An OData-specific error response (which can be recognized by the presence of the <a href="#HeaderODataVersion"><code>OData-Version</code></a> header) is format-specific and consists at least of the following information:</p>
 <ul>
 <li><code>code</code>: required non-null, non-empty, language-independent string. Its value is a service-defined error code. This code serves as a sub-status for the HTTP error code specified in the response.</li>
 <li><code>message</code>: required non-null, non-empty, language-dependent, human-readable string describing the error. The <a href="#HeaderContentLanguage"><code>Content-Language</code></a> header MUST contain the language code from <a href="#rfc5646">RFC5646</a> corresponding to the language in which the value for message is written.</li>

docs/odata-protocol/odata-protocol.md

@@ -1911,7 +1911,9 @@ include a response body describing the functionality not implemented.
 
 ## <a name="ErrorResponseBody" href="#ErrorResponseBody">9.4 Error Response Body</a>
 
-The representation of an error response body is format-specific. It
+An error response body can be the result of a failure of OData processing or of the underlying infrastructure.
+An OData-specific error response (which can be recognized by the presence
+of the [`OData-Version`](#HeaderODataVersion) header) is format-specific and
 consists at least of the following information:
 - `code`: required non-null, non-empty,
 language-independent string. Its value is a service-defined error code.

odata-protocol/8 Header Fields.md

@@ -1037,7 +1037,9 @@ include a response body describing the functionality not implemented.
 
 ## ##subsec Error Response Body
 
-The representation of an error response body is format-specific. It
+An error response body can be the result of a failure of OData processing or of the underlying infrastructure.
+An OData-specific error response (which can be recognized by the presence
+of the [`OData-Version`](#HeaderODataVersion) header) is format-specific and
 consists at least of the following information:
 - `code`: required non-null, non-empty,
 language-independent string. Its value is a service-defined error code.