How does COMSOL treat a line source in 3D?

Hello everybody,

I am simulating a heat transfer problem which incorporates line sources. Does anybody know how COMSOL deals with the singularities?

Are nodal points set on the line source?
When calculating the temperature on the line, does COMSOL simply interpolate between the temperature of adjacent cells?

In the user's guide, it only says that "The finite element discretization used in COMSOL returns a finite temperature distribution along the line, but that distribution must be interpreted in a weak sense."

Thank you very much! Best regards,
Koenraad