diff --git a/src/yang/etsi-nfv-vnf.yang b/src/yang/etsi-nfv-vnf.yang
index 19827899615e6ce07f260c63ff839136af1b3b71..dcc09c579333d3c9a74ad1a9f9692507c935c1c3 100755
--- a/src/yang/etsi-nfv-vnf.yang
+++ b/src/yang/etsi-nfv-vnf.yang
@@ -827,8 +827,26 @@ submodule etsi-nfv-vnf {
             "GS NFV IFA011: Section 7.1.6.5 SwImageDesc
              information element.";
         }
-        leaf checksum {
-          type string;
+        container checksum {
+          leaf algorithm {
+            type string;
+            description
+              "Species the algorithm used to obtain the checksum
+               value.";
+            reference
+              "GS NFV IFA011: Section 7.1.6.10 ChecksumData
+               information element.";
+	  }
+	  leaf hash {
+	    type string;
+	    description
+	      "Contains the result of applying the algorithm
+               indicated by the algorithm attribute to the data to
+               which this ChecksumData refers.";
+            reference
+              "GS NFV IFA011: Section 7.1.6.10 ChecksumData
+               information element.";
+	  }
           description
             "The checksum of the software image file.";
           reference
@@ -2304,7 +2322,23 @@ submodule etsi-nfv-vnf {
         leaf-list extension {
           type string;
           description
-            "'Extension' attributes of VnfInfo that are writeable.";
+            "Additional VNF-specific attributes of VnfInfo that
+             affect the lifecycle management of a VNF instance and
+             that are writeable.
+
+             For each VNF instance, these attributes are stored
+             persistently by the VNFM and can be queried and
+             modified through the VNFM.
+
+             These attributes are intended to be consumed by the
+             VNFM or by the lifecycle management scripts during the
+             execution of VNF lifecycle management operations.
+
+             Modifying these values has no direct effect on the VNF
+             instance; however, modified values can be considered
+             during subsequent VNF lifecycle management operations,
+             which means that the modified values can indirectly
+             affect the configuration of the VNF instance.";
           reference
             "GS NFV IFA011: Section 7.1.14 VnfInfoModifiableAttributes
              information element";
@@ -2312,7 +2346,22 @@ submodule etsi-nfv-vnf {
         leaf-list metadata {
           type string;
           description
-            "'Metadata' attributes of VnfInfo that are writeable.";
+            "Additional VNF-specific attributes of VnfInfo that are
+             writeable and that provide metadata describing the VNF
+             instance.
+
+             For each VNF instance, these attributes are stored
+             persistently by the VNFM and can be queried and modified
+             through the VNFM.
+
+             These attributes are intended to provide information to
+             functional blocks external to the VNFM and will not be
+             used by the VNFM or the VNF lifecycle management
+             scripts when executing lifecycle management operations.
+
+             Modifying these attributes has no effect on the VNF
+             instance. It only affects the attribute values stored by
+             the VNFM.";
           reference
             "GS NFV IFA011: Section 7.1.14 VnfInfoModifiableAttributes
              information element";