Why Dlinmod stability analysis allows positive eigenvalues

hello everyone,

On the official website about dlinmod. Computing the eigenvalues of the linearized matrix Ad provides an indication of the stability of the system. The system is stable if Ts>0 and the eigenvalues are within the unit circle. It means that system is still stable, when there are positive eigenvalues which are within the the unit circle. Is there any specific statement about this?

Thanks for answering.