diff --git a/conversion_utils/jos_msds_and_properties.py b/conversion_utils/jos_msds_and_properties.py
index 949b023..cd1cc02 100644
--- a/conversion_utils/jos_msds_and_properties.py
+++ b/conversion_utils/jos_msds_and_properties.py
@@ -259,7 +259,13 @@ class Converter:
 
     def is_valid_msd(self, msd):
         """Verify if the Msd code is in the standard JOS set."""
-        return msd.code in self.specifications.codes_map[msd.language]
+        code_map = self.specifications.codes_map[msd.language]
+        if msd.code in code_map:
+            return True
+        for msd_code in code_map:
+            if msd_code.startswith(msd.code):
+                return True
+        return False
 
     def check_valid_msd(self, msd, require_valid_flag):
         """If the Msd code is not valid, raise an exception or give a warning."""