added an intro to grouped annotations per Stevan

docs/eml-semantic-annotation-primer.md

@@ -203,12 +203,15 @@ Related FAQ: [Are all EML dataTable attributes measurements?](#FAQ-are-all-eml-a
 
 
 ### Annotations grouped under the EML `<annotations>` element
-The examples above show annotations directly beneath the *subject* element. However, annotations can also be grouped together, under an `<annotations>` element.  
+Examples 1-3 above show annotations directly beneath the a parent element that becomes the *semantic subject*. However, all the annotations for an entire dataset can be grouped together in two ways.   
 
-An annotation in the `annotations` element differs from Examples 1-3 above because the subject is directly referred to by a `references` attribute. Each `annotation` element has a `references` attribute that points to the `id` attribute of the element being annotated. That is, what is listed in the `references` attribute is the id of the subject of the semantic annotation. Any of the EML modules may be referenced by the `references` attribute and because ids are unique within an EML document, this is a single subject. 
+When the annotations are grouped together,  each `annotation` must have its subject designated by a `references` attribute that points to the `id` attribute of the element being annotated (the *subject*). 
+That is, what is listed in the `references` attribute is the id of the *subject* of the semantic annotation. This means that _any_ EML element with an id can become the subject of an annotation. 
 
 - The *subject* of the semantic statement is implicitly the element containing the referenced `id`. 
 
+There are two places where annotations can be grouped. The first is the `<annotations>` element ([Example 4](#eml-example-4)); the second is under `<additionalMetadata>` below, [Example 5](#eml-example-5).
+
 
 <a name="eml-example-4"></a>