Are Matlab/Simulink Solver validated?

Hi,

if you build a simulation in C/C++ or any other language it is necessary to verify and validate the solvers. Regarding Matlab/Simulink I never thought about this. So, my question is: are solvers in Matlab/Simulink verified and validated? Of course they are internally by Mathworks (at least I hope :) ) but are there any official documents (requirements, test documents, etc) or statesments of Mathworks for their solvers?

Thanks for any answers.

Florian