diff --git a/src/yang/etsi-nfv-common.yang b/src/yang/etsi-nfv-common.yang
index 23092426674b924167c950a593d8e903b548d710..b4a33eccb3045f3ff66a14f6b2336510fcac6bfd 100644
--- a/src/yang/etsi-nfv-common.yang
+++ b/src/yang/etsi-nfv-common.yang
@@ -254,13 +254,13 @@ submodule etsi-nfv-common {
   grouping connectivity-type {
     container connectivity-type {
       list layer-protocol {
-	key "protocol";
+        key "protocol";
 
-	leaf protocol {
+        leaf protocol {
           type identityref {
             base layer-protocol;
           }
-	}
+        }
         description
           "Identifies the protocols that the VL uses (Ethernet,
            MPLS, ODU2, IPV4, IPV6, Pseudo-Wire). The top layer
diff --git a/src/yang/etsi-nfv-ns.yang b/src/yang/etsi-nfv-ns.yang
index 93264f7ab05bd433cbbc7cf95eff1f66bc01ce4d..31a11c5b4c07bb78f43da7a9bcd96fbfbd9b54b6 100644
--- a/src/yang/etsi-nfv-ns.yang
+++ b/src/yang/etsi-nfv-ns.yang
@@ -250,6 +250,7 @@ submodule etsi-nfv-ns {
           }
 
           container qos {
+	    presence "VL QoS parameters";
             description
               "The QoS information element specifies quality of
                service parameters applicable to a VL.";
@@ -753,7 +754,7 @@ submodule etsi-nfv-ns {
           }
 
           leaf min-number-of-instances {
-            default 1;
+            default "1";
             type uint16;
             description
               "Minimum number of instances of the VNF based on this
@@ -764,7 +765,7 @@ submodule etsi-nfv-ns {
           }
 
           leaf max-number-of-instances {
-            default 1;
+            default "1";
             type uint16;
             description
               "Maximum number of instances of the VNF based on this
@@ -844,8 +845,8 @@ submodule etsi-nfv-ns {
                 }
                 description
                   "A reference to the descriptor of a connection point
-                   attached to one of the constituent VNFs and PNFs or to
-                   the descriptor of a NS SAP.";
+                   attached to one of the constituent VNFs and PNFs or
+                   to the descriptor of a NS SAP.";
                 reference
                   "GS NFV IFA014: Section 6.4.4.2 CpdPool information
                    element";
@@ -901,8 +902,8 @@ submodule etsi-nfv-ns {
               description
                 "Reference an NS VL profile.";
               reference
-                "GS NFV IFA014: Section 6.3.7.2, NsVirutalLinkConnectivity
-                 information element.";
+                "GS NFV IFA014: Section 6.3.7.2,
+                 NsVirutalLinkConnectivity information element.";
             }
 
             list constituent-cpd-id {
@@ -934,8 +935,8 @@ submodule etsi-nfv-ns {
                 }
                 description
                   "A reference to the descriptor of a connection point
-                   attached to one of the constituent VNFs and PNFs or to
-                   the descriptor of a NS SAP.";
+                   attached to one of the constituent VNFs and PNFs or
+                   to the descriptor of a NS SAP.";
                 reference
                   "GS NFV IFA014: Section 6.4.4.2 CpdPool information
                    element";
@@ -1177,7 +1178,7 @@ submodule etsi-nfv-ns {
             }
 
             leaf number-of-instances {
-              default 1;
+              default "1";
               type uint32;
               description
                 "Specifies the number of VNF instances required for
@@ -1237,7 +1238,7 @@ submodule etsi-nfv-ns {
             }
 
             leaf number-of-instances {
-              default 1;
+              default "1";
               type uint32;
               description
                 "Specifies the number of nested NS instances required
@@ -1343,7 +1344,7 @@ submodule etsi-nfv-ns {
           }
           leaf min-number-of-instances {
             type uint16;
-            default 1;
+            default "1";
             description
               "Minimum number of nested NS instances based on the
                referenced NSD that is permitted to exist for this
@@ -1354,7 +1355,7 @@ submodule etsi-nfv-ns {
           }
           leaf max-number-of-instances {
             type uint16;
-            default 1;
+            default "1";
             description
               "Maximum number of nested NS instances based on the
                referenced NSD that is permitted to exist for this
diff --git a/src/yang/etsi-nfv-vnf.yang b/src/yang/etsi-nfv-vnf.yang
index 3a202cbbda233a40d9e2bd8291658e7a7c642a45..debc75c2273ac1ec85bf9e8a7a9a29a5247d5271 100755
--- a/src/yang/etsi-nfv-vnf.yang
+++ b/src/yang/etsi-nfv-vnf.yang
@@ -70,6 +70,7 @@ submodule etsi-nfv-vnf {
       list network-interface-requirements {
         key "key";
         min-elements "1";
+        max-elements "1";
 
         leaf key {
           type string;
@@ -623,7 +624,7 @@ submodule etsi-nfv-vnf {
             type uint16 {
               range "1..max";
             }
-            default 1;
+            default "1";
             description
               "Number of virtual CPUs.";
             reference
@@ -827,6 +828,7 @@ submodule etsi-nfv-vnf {
             "GS NFV IFA011: Section 7.1.6.5 SwImageDesc
              information element.";
         }
+
         leaf checksum {
           type string;
           description
@@ -1041,6 +1043,7 @@ submodule etsi-nfv-vnf {
                information element.";
           }
           container qos {
+	    presence "VL QoS parameters.";
             description
               "QoS of the VL.";
             reference
@@ -1149,8 +1152,8 @@ submodule etsi-nfv-vnf {
             }
             leaf cpd {
 	      type leafref {
-		path "deref(../vdu-id)/../int-cpd/id";
-	      }
+                path "deref(../vdu-id)/../int-cpd/id";
+              }
             }
           }
         }