TDS exempt means that the owners of the home are exempt from providing any disclosure information. This is generally the case for homes that are bank owned or there has been a trustee sale. That is perhaps the owners of the home have passed away and the executors of the trust then sell the home.
In all these cases the people selling the home have never lived there and have no knowledge of any preexisting conditions thus they are exempt from having any disclosure responsibilities because they have never been in the home or know little/nothing about the home.