Add WMS query template docs

grid_models.md

@@ -55,6 +55,13 @@ $ gdal_translate -ot Int16 -of GTiff -b 1 NETCDF:"tmp/result.nc":WARNING_STATUS
 ### Set up a WMS (Web Map Service)
 [Introduction to WMS (Wikipedia)](https://en.wikipedia.org/wiki/Web_Map_Service)
 
+A WMS can be created using server platforms such as:
+* [MapServer](https://mapserver.org/)
+* [GeoServer](https://geoserver.org/)
+* [ArcGIS server](https://enterprise.arcgis.com/en/server/) (proprietary)
+
+The code/configuration examples below are for MapServer.
+
 ## The structure of the WMS
 VIPS expects the WMS to follow certain patterns in order to display it in a map.
 
@@ -123,6 +130,42 @@ LAYER
 ```
 This will result in correct color presentation in the map, and the availability of a legend for the map (see the upper right corner in the screenshot above)
 
+### WMS queries
+
+A feature request to a WMS layer should get an XML response following this structure
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<vipsResult>
+    <modelName value="Carrot rust fly temperature model"/>
+    <modelId value="PSILARTEMP"/>
+    <!--[ACTUAL DATA]-->
+</vipsResult>
+```
+
+The `[ACTUAL_DATA]` are elements with parameter names and values. For instance:
+```xml
+<!--mapserver template-->
+<?xml version="1.0" encoding="UTF-8"?>
+<vipsResult>
+    <modelName value="Carrot rust fly temperature model"/>
+    <modelId value="PSILARTEMP"/>
+    <parameter name="DD" value="46.2"/> <!-- Day degrees for the selected location at a given time -->
+</vipsResult>
+```
+
+If you click on the WARNING_STATUS layer, you get a special response, the `warningStatus` element:
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<vipsResult>
+    <modelName value="Carrot rust fly temperature model"/>
+    <modelId value="PSILARTEMP"/>
+    <warningStatus value="3"/> <!-- Moderate infection risk for the selected location at a given time -->
+</vipsResult>
+```
+
+
+
 ### Multi language support
 Mapserver supports the &language=[language code] query parameter. Read more about the specifics [here](https://mapserver.org/ogc/inspire.html). Through this, we have been able to add language specific titles and abstracts. See an example below