Hi Bruno,
I know Timestamp team have already discovered the answer, but simply sharing for the rest of the community:
In the core IFS software, there is no way to restrict Labor Classes to Work Centers.
This can be resolved through a simple customization where all valid Labor Classes that belong to a certain Work Center are added as a custom “Labor Class” tab under the “Work Center” page. This involves creating a Custom Logical Unit for labor classes.
Next, a Custom Event ensures that only Labor Classes that exist on the Custom Logical Unit can be connected to fields such as Labor Class & Setup Labor Class.
Kind Regards,
Sayeef