lab4.md

@@ -97,6 +97,7 @@ PREFIX properties: <http://www.ida.liu.se/~TDDE05/properties>
 SELECT ?x ?y FROM 'salientpoints' WHERE { <someid> a <someklass> ;
               properties:location [ gis:x ?x; gis:y ?y ] . }
 ```
+* Take into account the following when calling this query:
   - Make sure to keep `<` and `>` they indicate a URI in the query, without them the query is invalid and will not be executed, so you can replace `<someid>` by `<somethingelse>` but not `somethingelse`.
   - Replace `salientpoints` with the TST parameter for `graphname`.
   - This query need to be executed with a service call to `/kDBServerNodelet/sparql_query`. You can check the official tutorial for [Python](https://docs.ros.org/en/galactic/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Py-Service-And-Client.html) or [C++](https://docs.ros.org/en/galactic/Tutorials/Beginner-Client-Libraries/Writing-A-Simple-Cpp-Service-And-Client.html) to learn how to make a service call.