diff --git a/SAS/OTDB/sql/create_base_tables.sql b/SAS/OTDB/sql/create_base_tables.sql
index 6483d8a97c1f0c1a532923d9d01d99c322332747..660123e3581e5932f4bad42c1acaff3aaaf6c68e 100644
--- a/SAS/OTDB/sql/create_base_tables.sql
+++ b/SAS/OTDB/sql/create_base_tables.sql
@@ -188,6 +188,7 @@ INSERT INTO unit values (9,  'MB/s',	'MB/s',	 '',			true);
 INSERT INTO unit values (10, 'Hz',		'Hz',	 '',			true);
 INSERT INTO unit values (11, 'kHz',		'kHz',	 '',			true);
 INSERT INTO unit values (12, 'MHz',		'MHz',	 '',			true);
+INSERT INTO unit values (13, 'period',  's|m|h', '',			false);
 
 --
 -- Treetype table