diff --git a/StandardizedVocabularies/CONCEPT_ANCESTOR.md b/StandardizedVocabularies/CONCEPT_ANCESTOR.md
index 56a6ae0..4639a62 100644
--- a/StandardizedVocabularies/CONCEPT_ANCESTOR.md
+++ b/StandardizedVocabularies/CONCEPT_ANCESTOR.md
@@ -9,8 +9,33 @@ Field|Required|Type|Description
 |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.|
 
+A path between two concepts can be characterized by the sequence of relationships that need to be traversed in order to reach a descendant concept from an ancestor concept.
+
+For example, for concepts
+
+descendant_concept_id|descendant_concept_name|ancestor_concept_id|ancestor_concept_name|min_levels_of_separation|max_levels_of_separation
+:----------|:--------------------|:--------|:---------------------|:----------|:-----------
+|313217|Atrial fibrillation|321588|Heart disease|3|4|
+
+the shortest path in concept_relationship will be :
+
+313217 Atrial fibrillation  **Is a**  4226399 Fibrillation  **Is a**
+44784217 Cardiac arrhythmia  **Is a**  321588  Heart disease
+
+the longest:
+
+313217 Atrial fibrillation  **Is a**  4068155  Atrial arrhythmia  **Is a** 
+4248028  Supraventricular arrhythmia  **Is a**  44784217 Cardiac arrhythmia 
+**Is a** 321588  Heart disease
+
+
+
+![](http://www.ohdsi.org/web/wiki/lib/exe/fetch.php?cache=&media=documentation:cdm:concept_ancestor.png)
+
+
+
 ### 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.
+  * Usually, only Concepts of the same Domain are connected through records of the CONCEPT_ANCESTOR table, but there might be exceptions.
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