diff --git a/BigQuery/OMOP CDM bigquery ddl.txt b/BigQuery/OMOP CDM bigquery ddl.txt
index 2bc4bb37..ae01b792 100644
--- a/BigQuery/OMOP CDM bigquery ddl.txt	
+++ b/BigQuery/OMOP CDM bigquery ddl.txt	
@@ -17,7 +17,7 @@ create table vocabulary (
   vocabulary_id			    varchar(20)		not null,
   vocabulary_name		    varchar(255)	not null,
   vocabulary_reference	varchar(255)	not null,
-  vocabulary_version	  varchar(255)	not null,
+  vocabulary_version	  varchar(255)	null,
   vocabulary_concept_id	integer			  not null
 )
 ;
diff --git a/Documentation/CommonDataModel_Wiki_Files/StandardizedVocabularies/VOCABULARY.md b/Documentation/CommonDataModel_Wiki_Files/StandardizedVocabularies/VOCABULARY.md
index 3ae2c263..4f243c28 100644
--- a/Documentation/CommonDataModel_Wiki_Files/StandardizedVocabularies/VOCABULARY.md
+++ b/Documentation/CommonDataModel_Wiki_Files/StandardizedVocabularies/VOCABULARY.md
@@ -5,7 +5,7 @@ Field|Required|Type|Description
 |vocabulary_id|Yes|varchar(20)|A unique identifier for each Vocabulary, such as ICD9CM, SNOMED, Visit.|
 |vocabulary_name|Yes|varchar(255)|The name describing the vocabulary, for example "International Classification of Diseases, Ninth Revision, Clinical Modification, Volume 1 and 2 (NCHS)" etc.|
 |vocabulary_reference|Yes|varchar(255)|External reference to documentation or available download of the about the vocabulary.|
-|vocabulary_version|Yes|varchar(255)|Version of the Vocabulary as indicated in the source.|
+|vocabulary_version|No|varchar(255)|Version of the Vocabulary as indicated in the source.|
 |vocabulary_concept_id|Yes|integer|A foreign key that refers to a standard concept identifier in the CONCEPT table for the Vocabulary the VOCABULARY record belongs to.|
 
 ### Conventions
diff --git a/Netezza/OMOP CDM netezza ddl.txt b/Netezza/OMOP CDM netezza ddl.txt
index 268eb262..d8014b63 100644
--- a/Netezza/OMOP CDM netezza ddl.txt	
+++ b/Netezza/OMOP CDM netezza ddl.txt	
@@ -64,7 +64,7 @@ CREATE TABLE vocabulary (
   vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 DISTRIBUTE ON RANDOM
diff --git a/Oracle/OMOP CDM oracle ddl.txt b/Oracle/OMOP CDM oracle ddl.txt
index c8627f24..99ddc8ea 100644
--- a/Oracle/OMOP CDM oracle ddl.txt	
+++ b/Oracle/OMOP CDM oracle ddl.txt	
@@ -62,7 +62,7 @@ CREATE TABLE vocabulary (
   vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 ;
diff --git a/ParallelDataWarehouse/OMOP CDM pdw ddl.txt b/ParallelDataWarehouse/OMOP CDM pdw ddl.txt
index 4f21f38f..d36a5f17 100644
--- a/ParallelDataWarehouse/OMOP CDM pdw ddl.txt	
+++ b/ParallelDataWarehouse/OMOP CDM pdw ddl.txt	
@@ -60,7 +60,7 @@ WITH (DISTRIBUTION = REPLICATE);
 IF XACT_STATE() = 1 COMMIT; CREATE TABLE  vocabulary  (vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 WITH (DISTRIBUTION = REPLICATE);
diff --git a/PostgreSQL/OMOP CDM postgresql ddl.txt b/PostgreSQL/OMOP CDM postgresql ddl.txt
index 24abfeab..9753bb89 100644
--- a/PostgreSQL/OMOP CDM postgresql ddl.txt	
+++ b/PostgreSQL/OMOP CDM postgresql ddl.txt	
@@ -62,7 +62,7 @@ CREATE TABLE vocabulary (
   vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 ;
diff --git a/Redshift/OMOP CDM redshift ddl.txt b/Redshift/OMOP CDM redshift ddl.txt
index 52a3bbcc..63e5c59a 100644
--- a/Redshift/OMOP CDM redshift ddl.txt	
+++ b/Redshift/OMOP CDM redshift ddl.txt	
@@ -60,7 +60,7 @@ DISTSTYLE ALL;
 CREATE TABLE vocabulary  (vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 DISTSTYLE ALL;
diff --git a/Sql Server/OMOP CDM sql server ddl.txt b/Sql Server/OMOP CDM sql server ddl.txt
index ea84452b..6dc13b5e 100644
--- a/Sql Server/OMOP CDM sql server ddl.txt	
+++ b/Sql Server/OMOP CDM sql server ddl.txt	
@@ -62,7 +62,7 @@ CREATE TABLE vocabulary (
   vocabulary_id			    VARCHAR(20)		NOT NULL,
   vocabulary_name		    VARCHAR(255)	NOT NULL,
   vocabulary_reference	VARCHAR(255)	NOT NULL,
-  vocabulary_version	  VARCHAR(255)	NOT NULL,
+  vocabulary_version	  VARCHAR(255)	NULL,
   vocabulary_concept_id	INTEGER			  NOT NULL
 )
 ;