updated readme
diff --git a/README.md b/README.md
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+++ b/README.md
@@ -22,7 +22,8 @@
 
 1. Git clone of Ansible configuration file templates
 
-1. Git clone of inventory file templates
+1. Git clone of inventory file templates. [How to setup your inventory 
+file](inventory)
 
 1. Create credentials.yml template file
 
@@ -71,4 +72,5 @@
 --- | --- |
 secure_aws_region | Please provide your ec2_region. |
 aws_access_key_id | Please provide your AWS Access Key ID. |
-aws_secret_access_key | Please provide your AWS Secret Access Key. |
\ No newline at end of file
+aws_secret_access_key | Please provide your AWS Secret Access Key. |
+
diff --git a/inventory.md b/inventory.md
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+Updating your inventory file
+============================
+
+We use a standard Ansible inventory file with some semantic conventions 
+applied to Ansible groups. The semantic model applied to the Ansible 
+inventory file is described in the following sections.
+ 
+## Ansible Inventory Files
+Ansible provides rich semantics for inventory files. We leverage the 
+ansible model by applying a semantic convention that is based on the 
+Apigee Private Cloud domain model for referencing server nodes as 
+collections of planets and regions. This means that the normal Ansible 
+inventory files are used as is with the exception of the semantic 
+conventions for inventory group names. 
+
+## Inventory File Conventions
+These roles depend on use of conventions in the inventory file. 
+Specifically inventory file conventions are ansible groups names that 
+are defined around Apigee semantics. These ansible groups are 
+semantically linked to the documentation. The ansible groups used as 
+conventions correspond to the installation roles and server 
+categorizations called out in the Apigee Private Cloud Installation and 
+Configuration Guide. It has been useful to use planet and region 
+designations combined with the documented installation role names to 
+create categorization semantics that should be fairly intuitive once you 
+read the Apigee Private Cloud Installation and Configuration Guide. 
+   
+## Inventory Planet, Region and Installation Role Conventions
+A planet refers to all server nodes across all data centers. These 
+semantics are held via the use of group names for all nodes that fulfill 
+a specific purpose. The installation roles provide the semantic model we 
+followed. The inventory file group names for planet level semantics are 
+listed in the template inventory file below. 
+
+A region represents subset of a planet. The semantics used for 
+installation roles are congruent with a region. Region have been 
+referenced as data centers. The internal configurations of OPDK and BaaS 
+support many regions as dc-1, dc-2 and so forth. Following this 
+historical precedent we also define the regions with their corresponding 
+installation role to provide a semantic model as follows:
+ 
+    # Listing that references all data centers that compose a planet. 
+    [planet]
+    dc-1
+
+    [dc-1]
+    # Listing of all nodes in data center 1 (dc-1)
+    
+    [ds:children]
+    # Listing of all the Cassandra and Zookeeper nodes across the planet
+    dc-1-ds
+    
+    [dc-1-ds]
+    # Listing of all the Cassandra and Zookeeper nodes in dc-1
+    
+    [dc-1-ms]
+    # Listing of all the Management Server nodes in dc-1
+     
+    [dc-1-ldap]
+    # Listing of all OpenLDAP nodes in dc-1
+    
+    [dc-1-rmp]
+    # Listing of all Router and Message Processor nodes in dc-1
+    
+    [dc-1-qpid]
+    # Listing of all Qpid nodes in dc-1
+    
+    [dc-1-pg]
+    # Listing of all Postgres nodes in dc-1
+    
+    [dc-1-pgmaster]
+    # Listing of the single Postgres master node in dc-1
+    
+    [dc-1-pgstandby]
+    # Listing of the single Postgres standby node in dc-1
+    
+    [dc-1-ui]
+    # Listing of the UI node in dc-1
+    
+## Zookeeper Observer Nodes
+Zookeeper nodes can be designated as an observer node. Ansible inventory 
+files allow variables to be assigned to servers. These roles will update 
+the silent installation configuration file correctly for any zookeeper 
+node that is assigned the variable zk_observer.
+  
+     zk_observer=true