Update CHANGES.md

CHANGES.md

@@ -69,8 +69,7 @@ parsing project URLs, see [`05e692d`](https://github.com/3dcitydb/3dcitydb-web-m
         | gmlid1  | value1  | value2  | value3  | value4  |
         | gmlid2  | value1  | value2  | value3  | value4  |
 
-
-    + Vertical: each object attribute is stored in one row consisting of three columns `ID`, 
+    + **Vertical**: each object attribute is stored in one row consisting of three columns `ID`, 
     `Attribute` and `Value`, which means an ID may occur in multiple rows in the table.
 
       **Note**: A vertical table must contain exactly 3 columns in this exact order: `gmlid`, `attribute` and `value`.
@@ -87,6 +86,21 @@ parsing project URLs, see [`05e692d`](https://github.com/3dcitydb/3dcitydb-web-m
         | gmlid2  | attribute2  | value2  |
         | gmlid2  | attribute3  | value3  |
         | gmlid2  | attribute4  | value4  |
+
+    + The response from PostgREST service is encoded in JSON with the following structure:
+    Both the horizontal and vertical mode consist of an array of records marked by the `[ ... ]`. 
+    Each record represents a line in the table, where:
+
+        + Each record in vertical mode only has exactly 3 elements: `gmlid`, attribute name and attribute value. The `gmlids` here can be duplicated in other records, but the combination of these 3 elements must be unique.
+           ```
+           [
+              { gmlid : "id1", value_name : "value_name", value : "value" },
+              { gmlid : "id2", value_name : "value_name", value : "value" },
+              ...
+           ]
+           ```
+
+        + On the other hand, each record in the horizontal mode can have more than 2 elements, but the first one must always be `gmlid` and this must be unique for each record.
 
 ##### UPDATES
 * Added support for `thematicDataSource` in URLs generated by `Generate Scene Link` as well as parsing project URLs, see[`85afb36`](https://github.com/3dcitydb/3dcitydb-web-map/commit/85afb36a840e044e03b95ade41ee6776840387a4).