diff --git a/api/gateway/share.go b/api/gateway/share.go
index 372920a21d..c9dec071f3 100644
--- a/api/gateway/share.go
+++ b/api/gateway/share.go
@@ -137,5 +137,5 @@ func parseGetByNamespaceArgs(r *http.Request) (height uint64, namespace share.Na
 	if err != nil {
 		return 0, nil, err
 	}
-	return height, namespace, namespace.ValidateDataNamespace()
+	return height, namespace, namespace.ValidateForData()
 }
diff --git a/blob/blob.go b/blob/blob.go
index 890601e1c8..e9ad2b6255 100644
--- a/blob/blob.go
+++ b/blob/blob.go
@@ -120,7 +120,7 @@ func NewBlob(shareVersion uint8, namespace share.Namespace, data []byte) (*Blob,
 	if len(data) == 0 || len(data) > appconsts.DefaultMaxBytes {
 		return nil, fmt.Errorf("blob data must be > 0 && <= %d, but it was %d bytes", appconsts.DefaultMaxBytes, len(data))
 	}
-	if err := namespace.ValidateBlobNamespace(); err != nil {
+	if err := namespace.ValidateForBlob(); err != nil {
 		return nil, err
 	}
 
diff --git a/share/getters/ipld.go b/share/getters/ipld.go
index 5633b03ad3..92d1c55678 100644
--- a/share/getters/ipld.go
+++ b/share/getters/ipld.go
@@ -98,7 +98,7 @@ func (ig *IPLDGetter) GetSharesByNamespace(
 		utils.SetStatusAndEnd(span, err)
 	}()
 
-	if err = namespace.ValidateDataNamespace(); err != nil {
+	if err = namespace.ValidateForData(); err != nil {
 		return nil, err
 	}
 
diff --git a/share/getters/shrex.go b/share/getters/shrex.go
index 479ff4be7f..6a2ac03dcd 100644
--- a/share/getters/shrex.go
+++ b/share/getters/shrex.go
@@ -190,7 +190,7 @@ func (sg *ShrexGetter) GetSharesByNamespace(
 	root *share.Root,
 	namespace share.Namespace,
 ) (share.NamespacedShares, error) {
-	if err := namespace.ValidateDataNamespace(); err != nil {
+	if err := namespace.ValidateForData(); err != nil {
 		return nil, err
 	}
 	var (
diff --git a/share/getters/store.go b/share/getters/store.go
index 47cf3d7cc3..0b88d89155 100644
--- a/share/getters/store.go
+++ b/share/getters/store.go
@@ -103,7 +103,7 @@ func (sg *StoreGetter) GetSharesByNamespace(
 		utils.SetStatusAndEnd(span, err)
 	}()
 
-	if err = namespace.ValidateDataNamespace(); err != nil {
+	if err = namespace.ValidateForData(); err != nil {
 		return nil, err
 	}
 
diff --git a/share/namespace.go b/share/namespace.go
index 111a2536b9..433529a57f 100644
--- a/share/namespace.go
+++ b/share/namespace.go
@@ -20,6 +20,7 @@ var (
 	ReservedPaddingNamespace = Namespace(appns.ReservedPaddingNamespace.Bytes())
 	TxNamespace              = Namespace(appns.TxNamespace.Bytes())
 	PayForBlobNamespace      = Namespace(appns.PayForBlobNamespace.Bytes())
+	ISRNamespace             = Namespace(appns.IntermediateStateRootsNamespace.Bytes())
 )
 
 // Namespace represents namespace of a Share.
@@ -40,7 +41,7 @@ func NewBlobNamespaceV0(id []byte) (Namespace, error) {
 	// version and zero padding are already set as zero,
 	// so simply copying subNID to the end is enough to comply the V0 spec
 	copy(n[len(n)-len(id):], id)
-	return n, n.ValidateBlobNamespace()
+	return n, n.ValidateForBlob()
 }
 
 // NamespaceFromBytes converts bytes into Namespace and validates it.
@@ -104,8 +105,8 @@ func (n Namespace) Validate() error {
 	return nil
 }
 
-// ValidateDataNamespace checks if the Namespace contains real/useful data.
-func (n Namespace) ValidateDataNamespace() error {
+// ValidateForData checks if the Namespace is of real/useful data.
+func (n Namespace) ValidateForData() error {
 	if err := n.Validate(); err != nil {
 		return err
 	}
@@ -115,9 +116,9 @@ func (n Namespace) ValidateDataNamespace() error {
 	return nil
 }
 
-// ValidateBlobNamespace checks if the Namespace is valid blob namespace.
-func (n Namespace) ValidateBlobNamespace() error {
-	if err := n.ValidateDataNamespace(); err != nil {
+// ValidateForBlob checks if the Namespace is valid blob namespace.
+func (n Namespace) ValidateForBlob() error {
+	if err := n.ValidateForData(); err != nil {
 		return err
 	}
 	if bytes.Compare(n, MaxReservedNamespace) < 1 {
diff --git a/share/p2p/shrexnd/client.go b/share/p2p/shrexnd/client.go
index c18b15476e..7f12c21cf2 100644
--- a/share/p2p/shrexnd/client.go
+++ b/share/p2p/shrexnd/client.go
@@ -53,7 +53,7 @@ func (c *Client) RequestND(
 	namespace share.Namespace,
 	peer peer.ID,
 ) (share.NamespacedShares, error) {
-	if err := namespace.ValidateDataNamespace(); err != nil {
+	if err := namespace.ValidateForData(); err != nil {
 		return nil, err
 	}
 
diff --git a/share/p2p/shrexnd/server.go b/share/p2p/shrexnd/server.go
index 112a8016b9..d61e6b2e68 100644
--- a/share/p2p/shrexnd/server.go
+++ b/share/p2p/shrexnd/server.go
@@ -147,7 +147,7 @@ func (srv *Server) handleNamespacedData(ctx context.Context, stream network.Stre
 
 // validateRequest checks correctness of the request
 func validateRequest(req pb.GetSharesByNamespaceRequest) error {
-	if err := share.Namespace(req.Namespace).ValidateDataNamespace(); err != nil {
+	if err := share.Namespace(req.Namespace).ValidateForData(); err != nil {
 		return err
 	}
 	if len(req.RootHash) != sha256.Size {
diff --git a/share/sharetest/testing.go b/share/sharetest/testing.go
index 76a0287030..50eb0eb003 100644
--- a/share/sharetest/testing.go
+++ b/share/sharetest/testing.go
@@ -45,7 +45,7 @@ func RandV0Namespace() share.Namespace {
 	rndMu.Unlock()
 	for {
 		namespace, _ := share.NewBlobNamespaceV0(rb)
-		if err := namespace.ValidateDataNamespace(); err != nil {
+		if err := namespace.ValidateForData(); err != nil {
 			continue
 		}
 		return namespace
diff --git a/state/core_access.go b/state/core_access.go
index 97880c5f3a..3fefaa3ed9 100644
--- a/state/core_access.go
+++ b/state/core_access.go
@@ -168,7 +168,7 @@ func (ca *CoreAccessor) SubmitPayForBlob(
 
 	appblobs := make([]*apptypes.Blob, len(blobs))
 	for i, b := range blobs {
-		if err := b.Namespace().ValidateBlobNamespace(); err != nil {
+		if err := b.Namespace().ValidateForBlob(); err != nil {
 			return nil, err
 		}
 		appblobs[i] = &b.Blob