In a page with Programma objects I want to you a grid selector to select Cursus objects to add to the reference set but only if both share the same reference to an Opl object. I tried many ways but it does not work, reason I Need xpath as source for the grid is the option to count/sum columns... I solved the reference problem for now but I am curious what the xpath shoueld be, if possible... see part of model here
1 answers

From your "Cursus" reference selector, you could use the following xpath to restrict the datagrid to show only courses related to the "opl" for the selected "Programma".

[CursusOpl/Opl/ProgrammaOpl = '%CurrentObject%'], where CurrentObject is the Program.

If you have any questions, let me know :-)