diff --git a/api/openapi_extensions.md b/api/openapi_extensions.md
index 9f4745fd..339452ba 100644
--- a/api/openapi_extensions.md
+++ b/api/openapi_extensions.md
@@ -21,3 +21,25 @@ Example:
     name: fields...
     type: string
 ```
+
+## Using oneOf to provide type alternatives
+
+<!-- TODO: Remove this section after upgrading to OpenAPI v3 -->
+
+`oneOf` (available in JSON Schema and Swagger/OpenAPI v3 but not in v2)
+is used in cases when a simpler type specification as a list of types
+doesn't work, as in the following example:
+```
+  properties:
+    old: # compliant with old Swagger
+      type:
+        - string
+        - object # Cannot specify a schema here
+    new: # uses oneOf extension
+      oneOf:
+        - type: string
+        - type: object
+          title: CustomSchemaForTheWin
+          properties:
+            ...
+```
diff --git a/scripts/templating/matrix_templates/units.py b/scripts/templating/matrix_templates/units.py
index 88f7b86c..90a87cd4 100644
--- a/scripts/templating/matrix_templates/units.py
+++ b/scripts/templating/matrix_templates/units.py
@@ -286,7 +286,9 @@ def get_json_schema_object_fields(obj, enforce_title=False):
 def process_data_type(prop, required=False, enforce_title=True):
     prop = inherit_parents(prop)
 
-    prop_type = prop['type']
+    prop_type = prop.get('oneOf', prop.get('type', []))
+    assert prop_type
+
     tables = []
     enum_desc = None
     is_object = False
@@ -317,6 +319,19 @@ def process_data_type(prop, required=False, enforce_title=True):
             tables = nested["tables"]
             enum_desc = nested["enum_desc"]
 
+    elif isinstance(prop_type, list):
+        prop_title = []
+        for t in prop_type:
+            if isinstance(t, dict):
+                nested = process_data_type(t)
+                tables.extend(nested['tables'])
+                prop_title.append(nested['title'])
+                # Assuming there's at most one enum among type options
+                enum_desc = nested['enum_desc']
+                if enum_desc:
+                    enum_desc = "%s if the type is enum" % enum_desc
+            else:
+                prop_title.append(t)
     else:
         prop_title = prop_type