diff --git a/.gitignore b/.gitignore
index 0790e0b..1952510 100644
--- a/.gitignore
+++ b/.gitignore
@@ -23,4 +23,7 @@
 hs_err_pid*
 /.project
 
-node_modules/
\ No newline at end of file
+node_modules/
+
+# reduction reports
+rpt_*
\ No newline at end of file
diff --git a/src/clear_unused.py b/src/clear_unused.py
new file mode 100644
index 0000000..809e012
--- /dev/null
+++ b/src/clear_unused.py
@@ -0,0 +1,63 @@
+import yaml
+
+working_dir = "../"
+input_file = working_dir + "/OSCALRestOpenAPI.yaml"
+output_file = working_dir + "/OSCALRestOpenAPI_REDUCED.yaml"
+in_use_file = working_dir + "/rpt_in_use_list.txt"
+removed_file = working_dir + "/rpt_removed_list.txt"
+
+ref_list = []
+remove_list = []
+
+def build_ref_list(key_name, item_key, item_value):
+    if item_key == key_name:
+        if item_value[0] == "#" and (item_value not in ref_list) :
+            print("+", end="")
+            ref_list.append(item_value)
+        else:
+            print("_", end="")
+    else:
+        print(".", end="")
+
+def lookup(key_name, data):
+    global ref_list
+    if isinstance(data, dict):
+        for item_key, item_value in data.items():
+            if isinstance(item_value, dict):
+                lookup(key_name, data[item_key])
+            else: # isinstance(item_value, list):
+                build_ref_list(key_name, key_name, item_value)
+
+
+def interrogate(top_level_key_name):
+    global ref_list
+    print("-- Checking " + top_level_key_name)
+    lookup("$ref", openAPI[top_level_key_name])
+    print()
+
+with open(input_file, 'r') as file:
+    openAPI = yaml.safe_load(file)
+
+print("Compiling list of references in use")
+interrogate("tags")
+interrogate("paths")
+
+with open(in_use_file, 'w') as file:
+        for line in ref_list:
+            file.write("%s\n" % line)
+
+print("Identifying schema definitions to remove")
+for item in openAPI["components"]["schemas"].keys():
+    if not "#/components/schemas/" + item in ref_list: 
+        remove_list.append(item)
+
+with open(removed_file, 'w') as file:
+        for line in remove_list:
+            file.write("%s\n" % line)
+
+for item in remove_list:
+    del openAPI["components"]["schemas"][item]
+        
+with open(output_file, 'w') as file:
+    yaml.dump(openAPI, file, sort_keys=False)
+