diff --git a/v2/session/grpc/service.pb.go b/v2/session/grpc/service.pb.go
index e18b8f3..223c38b 100644
Binary files a/v2/session/grpc/service.pb.go and b/v2/session/grpc/service.pb.go differ
diff --git a/v2/session/grpc/types.pb.go b/v2/session/grpc/types.pb.go
index fe557fd..aba3ceb 100644
Binary files a/v2/session/grpc/types.pb.go and b/v2/session/grpc/types.pb.go differ
diff --git a/v2/session/xheaders.go b/v2/session/xheaders.go
new file mode 100644
index 0000000..64b16de
--- /dev/null
+++ b/v2/session/xheaders.go
@@ -0,0 +1,16 @@
+package session
+
+// ReservedXHeaderPrefix is a prefix of keys to "well-known" X-headers.
+const ReservedXHeaderPrefix = "__NEOFS__"
+
+const (
+	// XHeaderNetmapEpoch is a key to the reserved X-header that specifies netmap epoch
+	// to use for object placement calculation. If set to '0' or not set, the current
+	// epoch only will be used.
+	XHeaderNetmapEpoch = ReservedXHeaderPrefix + "NETMAP_EPOCH"
+
+	// XHeaderNetmapLookupDepth is a key to the reserved X-header that limits
+	// how many past epochs back the node will can lookup. If set to '0' or not
+	// set, the current epoch only will be used.
+	XHeaderNetmapLookupDepth = ReservedXHeaderPrefix + "NETMAP_LOOKUP_DEPTH"
+)