Expand on processResponseEndOfBody values

Author: domenic

fetch.bs

@@ -7984,9 +7984,21 @@ in a <a for=/>parallel queue</a> if <a for=fetch><i>useParallelQueue</i></a> is
   <p>Takes an algorithm that will be passed a <a for=/>response</a> and null, failure, or a
   <a>byte sequence</a>. This is useful for standards that wish to operate on the entire
   <a for=/>response</a>'s <a for=response>body</a>, of which the result of reading it is supplied as
-  second argument.
+  second argument. The second argument's values have the following meaning:
 
-  <p>It might be surprising that a <a for=/>network error</a> will have null as second argument.
+  <dl>
+   <dt>null
+   <dd>The <a for=/>response</a>'s <a for=response>body</a> is null, due to the response being a
+   <a for=/>network error</a> or having a <a>null body status</a>.
+
+   <dt>failure
+   <dd>Attempting to <a for=body>fully read</a> the contents of the <a for=/>response</a>'s
+   <a for=response>body</a> failed, e.g., due to an I/O error.
+
+   <dt>a <a>byte sequence</a>
+   <dd><a for=body>Fully reading</a> the contents of the <a for=/>response</a>'s
+   <a for=response>body</a> succeeded.
+  </dl>
 
   <p class=warning>A standard that uses this argument cannot operate on <a for=/>response</a>'s
   <a for=response>body</a> itself as providing this argument will cause it to be read and it can be