diff --git a/StandardizedVocabularies/CONCEPT_ANCESTOR.md b/StandardizedVocabularies/CONCEPT_ANCESTOR.md
index 3bfb59d..e380919 100644
--- a/StandardizedVocabularies/CONCEPT_ANCESTOR.md
+++ b/StandardizedVocabularies/CONCEPT_ANCESTOR.md
@@ -1,10 +1,16 @@
-*OMOP Common Data Model v5.1 Specifications*
-<br>*Authors: Christian Reich, Patrick Ryan, Rimma Belenkaya, Karthik Natarajan, Clair Blacketer*
-<br>***Release date needed***
+The CONCEPT_ANCESTOR table is designed to simplify observational analysis by providing the complete hierarchical relationships between Concepts. Only direct parent-child relationships between Concepts are stored in the CONCEPT_RELATIONSHIP table. To determine higher level ancestry connections, all individual direct relationships would have to be navigated at analysis time. The  CONCEPT_ANCESTOR table includes records for all parent-child relationships, as well as grandparent-grandchild relationships and those of any other level of lineage. Using the CONCEPT_ANCESTOR table allows for querying for all descendants of a hierarchical concept. For example, drug ingredients and drug products are all descendants of a drug class ancestor.
 
-[Back to Table of Contents](https://github.com/OHDSI/CommonDataModel/blob/master/Documentation/TableofContents.md)
-<br>[Back to Standardized Vocabularies](StandardizedVocabularies.md)
+This table is entirely derived from the CONCEPT, CONCEPT_RELATIONSHIP and RELATIONSHIP tables.  
 
----
+Field|Required|Type|Description
+:----|:----|:----|:-----
+|ancestor_concept_id|Yes|integer|A foreign key to the concept in the concept table for the higher-level concept that forms the ancestor in the relationship.|
+|descendant_concept_id|Yes|integer|A foreign key to the concept in the concept table for the lower-level concept that forms the descendant in the relationship.|
+|min_levels_of_separation|Yes|integer|The minimum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis.|
+|max_levels_of_separation|Yes|integer|The maximum separation in number of levels of hierarchy between ancestor and descendant concepts. This is an attribute that is used to simplify hierarchic analysis.|
 
-# 3.8 CONCEPT_ANCESTOR
\ No newline at end of file
+## Conventions 
+
+  * Each concept is also recorded as an ancestor of itself.
+  * Only valid and Standard Concepts participate in the CONCEPT_ANCESTOR table. It is not possible to find ancestors or descendants of deprecated or Source Concepts.
+  * Usually, only Concepts of the same Domain are connected through records of the CONCEPT_ANCESTOR table, but there might be exceptions.