diff --git a/src/sonic-yang-models/yang-models/sonic-breakout_cfg.yang b/src/sonic-yang-models/yang-models/sonic-breakout_cfg.yang
index b8ae8efdf318..85c0cf997d40 100644
--- a/src/sonic-yang-models/yang-models/sonic-breakout_cfg.yang
+++ b/src/sonic-yang-models/yang-models/sonic-breakout_cfg.yang
@@ -7,7 +7,6 @@ module sonic-breakout_cfg {
 
     import sonic-extension {
         prefix ext;
-        revision-date 2019-07-01;
     }
 
     description "BREAKOUT_CFG YANG Module for SONiC OS";
diff --git a/src/sonic-yang-models/yang-models/sonic-crm.yang b/src/sonic-yang-models/yang-models/sonic-crm.yang
index 48c15b0e48cc..d1ac84eec391 100644
--- a/src/sonic-yang-models/yang-models/sonic-crm.yang
+++ b/src/sonic-yang-models/yang-models/sonic-crm.yang
@@ -7,7 +7,6 @@ module sonic-crm {
 
     import sonic-types {
         prefix stypes;
-        revision-date 2019-07-01;
     }
 
     description "CRM YANG Module for SONiC OS";
diff --git a/src/sonic-yang-models/yang-models/sonic-device_metadata.yang b/src/sonic-yang-models/yang-models/sonic-device_metadata.yang
index 217715858148..f7ef8261d6ba 100644
--- a/src/sonic-yang-models/yang-models/sonic-device_metadata.yang
+++ b/src/sonic-yang-models/yang-models/sonic-device_metadata.yang
@@ -15,7 +15,6 @@ module sonic-device_metadata {
 
     import sonic-types {
         prefix stypes;
-        revision-date 2019-07-01;
     }
 
     description "DEVICE_METADATA YANG Module for SONiC OS";
diff --git a/src/sonic-yang-models/yang-models/sonic-device_neighbor.yang b/src/sonic-yang-models/yang-models/sonic-device_neighbor.yang
index e1c745dd9afe..a7284ccec50c 100644
--- a/src/sonic-yang-models/yang-models/sonic-device_neighbor.yang
+++ b/src/sonic-yang-models/yang-models/sonic-device_neighbor.yang
@@ -11,7 +11,6 @@ module sonic-device_neighbor {
 
     import sonic-extension {
         prefix ext;
-        revision-date 2019-07-01;
     }
 
     import sonic-port {
diff --git a/src/sonic-yang-models/yang-models/sonic-extension.yang b/src/sonic-yang-models/yang-models/sonic-extension.yang
deleted file mode 100644
index 6369b605173c..000000000000
--- a/src/sonic-yang-models/yang-models/sonic-extension.yang
+++ /dev/null
@@ -1,13 +0,0 @@
-module sonic-extension {
-
-    yang-version 1.1;
-
-    namespace "http://github.com/Azure/sonic-extension";
-    prefix sonic-extension;
-
-    description "Extension yang Module for SONiC OS";
-
-    revision 2019-07-01 {
-        description "First Revision";
-    }
-}
diff --git a/src/sonic-yang-models/yang-models/sonic-interface.yang b/src/sonic-yang-models/yang-models/sonic-interface.yang
index f559eb6be1b6..746dbba46b7b 100644
--- a/src/sonic-yang-models/yang-models/sonic-interface.yang
+++ b/src/sonic-yang-models/yang-models/sonic-interface.yang
@@ -7,12 +7,10 @@ module sonic-interface {
 
 	import sonic-types {
 		prefix stypes;
-		revision-date 2019-07-01;
 	}
 
 	import sonic-extension {
 		prefix ext;
-		revision-date 2019-07-01;
 	}
 
 	import sonic-port {
diff --git a/src/sonic-yang-models/yang-models/sonic-loopback-interface.yang b/src/sonic-yang-models/yang-models/sonic-loopback-interface.yang
index 0414f3b94344..df59d3961fb4 100644
--- a/src/sonic-yang-models/yang-models/sonic-loopback-interface.yang
+++ b/src/sonic-yang-models/yang-models/sonic-loopback-interface.yang
@@ -7,12 +7,10 @@ module sonic-loopback-interface {
 
     import sonic-types {
         prefix stypes;
-        revision-date 2019-07-01;
     }
 
     import sonic-extension {
         prefix ext;
-        revision-date 2019-07-01;
     }
 
     import sonic-vrf {
diff --git a/src/sonic-yang-models/yang-models/sonic-port.yang b/src/sonic-yang-models/yang-models/sonic-port.yang
index d2f63e571207..0e1c5db0b8f0 100644
--- a/src/sonic-yang-models/yang-models/sonic-port.yang
+++ b/src/sonic-yang-models/yang-models/sonic-port.yang
@@ -7,12 +7,10 @@ module sonic-port{
 
 	import sonic-types {
 		prefix stypes;
-		revision-date 2019-07-01;
 	}
 
 	import sonic-extension {
 		prefix ext;
-		revision-date 2019-07-01;
 	}
 
 	description "PORT yang Module for SONiC OS";
diff --git a/src/sonic-yang-models/yang-models/sonic-portchannel.yang b/src/sonic-yang-models/yang-models/sonic-portchannel.yang
index 587a19e4bec6..083a413527ec 100644
--- a/src/sonic-yang-models/yang-models/sonic-portchannel.yang
+++ b/src/sonic-yang-models/yang-models/sonic-portchannel.yang
@@ -7,12 +7,10 @@ module sonic-portchannel {
 
     import sonic-types {
         prefix stypes;
-        revision-date 2019-07-01;
     }
 
     import sonic-extension {
         prefix ext;
-        revision-date 2019-07-01;
     }
 
     import sonic-port {
@@ -138,7 +136,7 @@ module sonic-portchannel {
                         path "/lag:sonic-portchannel/lag:PORTCHANNEL/lag:PORTCHANNEL_LIST/lag:name";
                     }
                 }
-        
+
                 leaf port {
                     /* key elements are mandatory by default */
                     type leafref {
diff --git a/src/sonic-yang-models/yang-models/sonic-vlan.yang b/src/sonic-yang-models/yang-models/sonic-vlan.yang
index f420b8f7b17c..3e4074428654 100644
--- a/src/sonic-yang-models/yang-models/sonic-vlan.yang
+++ b/src/sonic-yang-models/yang-models/sonic-vlan.yang
@@ -11,12 +11,10 @@ module sonic-vlan {
 
 	import sonic-types {
 		prefix stypes;
-		revision-date 2019-07-01;
 	}
 
 	import sonic-extension {
 		prefix ext;
-		revision-date 2019-07-01;
 	}
 
 	import sonic-port {
diff --git a/src/sonic-yang-models/yang-templates/sonic-extension.yang.j2 b/src/sonic-yang-models/yang-templates/sonic-extension.yang.j2
new file mode 100644
index 000000000000..142ef517b7c2
--- /dev/null
+++ b/src/sonic-yang-models/yang-templates/sonic-extension.yang.j2
@@ -0,0 +1,41 @@
+module sonic-extension {
+
+    yang-version 1.1;
+
+    namespace "http://github.com/Azure/sonic-extension";
+    prefix sonic-extension;
+
+    description "Extension yang Module for SONiC OS";
+
+    revision 2019-07-01 {
+        description "First Revision";
+    }
+
+    /* For complete guide of using these extensions in SONiC yangs, refer
+    SONiC yang guidelines at
+    https://github.com/Azure/SONiC/blob/master/doc/mgmt/SONiC_YANG_Model_Guidelines.md */
+
+    extension db-name {
+        description "DB name, e.g. APPL_DB, CONFIG_DB";
+        argument "value";
+    }
+
+    {% if yang_model_type == "cvl" %}
+    extension custom-validation-cvl {
+        description "Extension for registering cvl based custom validation handler.";
+        argument "handler";
+    }
+
+    extension dependent-on {
+        description
+            "Extension to define dependency on other table. During CREATE/UPDATE,
+            the action will be performed first on the Parent table and then on the
+            Dependent table. In DELETE operation, the Dependent table will be
+            deleted first and then the Parent table. This extension can be defined
+            only under List nodes. Table name should always be suffixed with '_LIST'
+            as modeled in yang.  e.g. - dependent-on STP_LIST";
+        argument "value";
+    }
+    {% else %}
+    {% endif %}
+}
diff --git a/src/sonic-yang-models/yang-models/sonic-types.yang b/src/sonic-yang-models/yang-templates/sonic-types.yang.j2
similarity index 74%
rename from src/sonic-yang-models/yang-models/sonic-types.yang
rename to src/sonic-yang-models/yang-templates/sonic-types.yang.j2
index 7bc9372536e8..c28ea16c00bd 100644
--- a/src/sonic-yang-models/yang-models/sonic-types.yang
+++ b/src/sonic-yang-models/yang-templates/sonic-types.yang.j2
@@ -155,6 +155,42 @@ module sonic-types {
         }
     }
 
+    typedef oper-status {
+        type enumeration {
+            enum unknown;
+            enum up;
+            enum down;
+        }
+        description "Operational status of an entity such as Port, MCLAG etc";
+    }
+
+    typedef mode-status {
+        type enumeration {
+            enum enable;
+            enum disable;
+        }
+        description
+            "This type can be used where toggle functionality required.
+            For ex. IPv6-link-local-only, Dhcp-replay-link-select, SNMP traps etc";
+    }
+
+    typedef dhcp-relay-policy-action {
+        type enumeration {
+            enum discard;
+            enum append;
+            enum replace;
+        }
+        description "DHCP relay policy action value";
+    }
+
+    typedef percentage {
+        type uint8 {
+            range "0..100";
+        }
+        description
+            "Integer indicating a percentage value";
+    }
+
     typedef tpid_type {
         type string {
             pattern "0x8100|0x9100|0x9200|0x88a8|0x88A8";
@@ -185,4 +221,27 @@ module sonic-types {
             enum transit;
         }
     }
+
+
+
+    /* Required for CVL */
+    {% if yang_model_type == "cvl" %}
+    container operation {
+        description
+            "This definition is used internally by CVL and
+            is not exposed in NBI. Leaf 'operation' allows
+            evaluation of must expression for
+            CREATE/UPDATE/DELETE operation.";
+
+        leaf operation {
+            type enumeration {
+                enum NOP;
+                enum CREATE;
+                enum UPDATE;
+                enum DELETE;
+            }
+        }
+    }
+    {% else %}
+    {% endif %}
 }