Clarification of some terms around Transaction Examples.

API Blueprint Specification.md

@@ -666,9 +666,9 @@ This section **may** include one nested [Attributes section][] defining the inpu
 
 Action section **should** include at least one nested [Response section](#def-response-section) and **may** include additional nested [Request](#def-request-section) and [Response](#def-response-section) sections.
 
-Nested Request and Response sections **may** be ordered into groups where each groups represent one transaction example. First transaction example group starts with the first nested Request or Response section. Subsequent groups start with the first nested Request section following a Response section.
+Nested Request and Response sections **may** be ordered into implicit groups where each such group represents one transaction example. First transaction example group starts with the first nested Request or Response section. Subsequent groups start with the first nested Request section following a Response section.
 
-Multiple Request and Response nested sections within one transaction example **should** have different identifiers.
+Multiple nested Request and Response sections within one transaction example **should** have different identifiers.
 
 #### Example
 

Glossary of Terms.md

@@ -6,9 +6,9 @@ A brief list of terms as used in the [API Blueprint](http://apiblueprint.org) co
 
 <a name="def-action"></a>
 ### Action
-An **HTTP transaction** (a request-response transaction).
+One or more [**HTTP Transactions**](#def-transaction) within a [Resource](#def-resource) with a common [HTTP Request Method](#def-method).
 
-Actions are specified by an [HTTP request method](#def-method) within a [resource](#def-resource).
+[Requests](#def-request) and [Responses](#def-response) within an Action may be ordered into implicit groups where each such group represents one [**HTTP Transaction Example**](#def-transaction-example).
 
 <a name="def-api"></a>
 ### API
@@ -48,7 +48,7 @@ An [**HTTP Request Method**](http://en.wikipedia.org/wiki/Hypertext_Transfer_Pro
 
 <a name="def-message"></a>
 ### Message
-An **HTTP transaction message**.
+An **HTTP ction message**.
 
 <a name="def-message-body"></a>
 ### Message body
@@ -83,18 +83,30 @@ A [**payload**](#def-payload) containing one specific [HTTP Response](http://www
 ### Resource
 An API [**resource**](http://www.w3.org/TR/di-gloss/#def-resource) specified by its *URI*. It can also refer to a [**set of resources**](#def-resource) matching one [**URI template**](#def-uri-template).
 
+<a name="def-resource-group"></a>
+### Resource Group
+An arbitrary grouping of one or more [**Resource Sets**](#def-resource-set).
+
 <a name="def-resource-model"></a>
 ### Resource Model
 One [**manifestation of a resource**](http://www.w3.org/TR/di-gloss/#def-resource-manifestation) in the form of a [payload](#def-payload). A resource model is an example representation of its resource. Can be referenced later in the place of a [payload](#def-payload).
 
 <a name="def-resource-set"></a>
 ### Resource Set
-A set of API [**resources**](http://www.w3.org/TR/di-gloss/#def-resource) its *URI* matches one specific  [**URI template**](#def-uri-template).
+A set of API [**resources**](http://www.w3.org/TR/di-gloss/#def-resource) with *URI*, which matches one specific [**URI template**](#def-uri-template).
 
 <a name="def-trait"></a>
 ### Trait
 A quality or characteristic of an API Blueprint SECTION.
 
+<a name="def-transaction"></a>
+### Transaction
+[HTTP Request](#def-request) with a corresponding [HTTP Response](#def-response).
+
+<a name="def-transaction-example"></a>
+### Transaction Example
+An implicit group of one or more [Requests](#def-request) and one or more corresponding [Responses](#def-response). If expanded into Request-Response pairs, it represents one or more [**HTTP Transactions**](#def-transaction).
+
 <a name="def-schema"></a>
 ### Schema
 A **validation schema** in a form of an [**asset**](#def-asset) used to validate (or describe) a [**message-body**](#def-message-body).
@@ -113,4 +125,3 @@ A compact sequence of characters for describing a range of **Uniform Resource Id
 
 
 [MSON]: https://github.com/apiaryio/mson
-