diff --git a/lib/xos-genx/xosgenx/jinja2_extensions/tosca.py b/lib/xos-genx/xosgenx/jinja2_extensions/tosca.py
new file mode 100644
index 0000000..04ac3ff
--- /dev/null
+++ b/lib/xos-genx/xosgenx/jinja2_extensions/tosca.py
@@ -0,0 +1,26 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+def xproto_fields_to_tosca_keys(fields):
+	keys = []
+	# look for explicit keys
+	for f in fields:
+		if 'tosca_key' in f['options'] and f['options']['tosca_key'] and 'link' not in f:
+			keys.append(f['name'])
+		if 'tosca_key' in f['options'] and f['options']['tosca_key'] and ('link' in f and f['link']):
+			keys.append("%s_id" % f['name'])
+	# if not keys are specified and there is a name field, use that as key.
+	if len(keys) == 0 and 'name' in map(lambda f: f['name'], fields):
+		keys.append('name')
+	return keys
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