CSpec-Registry-API.md

 ### Introduction to API Services
+
 [[_TOC_]]
 
 <div>
@@ -286,3 +287,180 @@ Response from the API endpoints can be filtered or restricted using the followin
 </tr>
 </table>
 
+---
+
+#### Key Fields in API Response
+
+The table below lists the key fields returned in the API response.
+
+<table>
+<tr>
+<td>
+
+**Key Fields**
+</td>
+<td>
+
+**Description**
+</td>
+<td>
+
+**Example**
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">ld</span>**
+</td>
+<td>
+
+<span dir="">This entity is a linked data object for these entities</span>
+</td>
+<td>
+
+<span dir="">"ld": \[  {  "CriteriaCode": \[ … \]</span> <span dir="">}, {"RuleSet": \[ … \]</span> <span dir="">}, { "Gene": \[ … \]  } \],</span>
+
+<span dir="">Here, "CriteriaCode", "RuleSet" and "Gene" are the linked data entities for the variant "CA000176"</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">ldFor</span>**
+</td>
+<td>
+
+<span dir="">This entity is linked data FOR these other entities</span>
+</td>
+<td>
+
+<span dir="">"ldFor": \[        {          "Gene": \[ … \]        }      \],</span>
+
+<span dir="">SequenceVariantInterpretation “CA000176” is linked data FOR the Gene “TP53”</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">entId</span>**
+</td>
+<td>
+
+<span dir="">Identifier of entity in the external data source</span>
+</td>
+<td>
+
+<span dir="">"entId": "GN016",</span>
+
+<span dir="">where "GN016" - ClinGen Allele Registry identifier for “SequenceVariantInterpretation”</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">entIri</span>**
+</td>
+<td>
+
+<span dir="">IRI of entity in the external data source</span>
+</td>
+<td>
+
+<span dir="">"entIri": "</span>[<span dir="">https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1097</span>](https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:1097)<span dir="">",</span>
+
+<span dir="">where the IRI is the “link” to this entity in the external data source</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">entType</span>**
+</td>
+<td>
+
+<span dir="">Type of entity</span>
+</td>
+<td>
+
+<span dir="">"entType": "SequenceVariantInterpretation",</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">ldhId</span>**
+</td>
+<td>
+
+<span dir="">CSpec identifier</span>
+
+<span dir="">_(Note: If data is embedded within CSpec, this will be the only identifier)_</span>
+</td>
+<td>
+
+<span dir="">"ldhId": "41889804",</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">ldhIri</span>**
+</td>
+<td>
+
+<span dir="">CSpec IRI</span>
+
+<span dir="">_(Note: If data is embedded within CSpec, this will be the only IRI)_</span>
+</td>
+<td>
+
+<span dir="">"ldhIri": "</span>[<span dir="">https://cspec.genome.network/cspec/SequenceVariantInterpretation/id/41889804</span>](https://cspec.genome.network/cspec/SequenceVariantInterpretation/id/41889804)<span dir="">"</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">entContent</span>**
+</td>
+<td>
+
+<span dir="">Excerpts from external data source</span>
+</td>
+<td>
+
+<span dir="">"entContent": {...}</span>
+
+<span dir="">The excerpt content will be different for each entity type. Detailed documentation for the excerpt content stored for each type of entity will be added soon.</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">modifier</span>**
+</td>
+<td>
+
+<span dir="">Person who added this entity to CSpec</span>
+</td>
+<td>
+
+<span dir="">"modifier": "johndoe",</span>
+</td>
+</tr>
+<tr>
+<td>
+
+**<span dir="">modified</span>**
+</td>
+<td>
+
+<span dir="">Modification timestamp value </span>
+</td>
+<td>
+
+<span dir="">"modified": "2019-10-03T17:04:35.395Z",</span>
+</td>
+</tr>
+</table>
+