Very high-speed, digital technology is imposing new requirements on test logic that will limit the effectiveness of current IEEE 1149.1 based testing. IEEE P1149.6 is an extension to IEEE 1149.1 that attempts to standardize the boundary-scan structures and methods required to ensure simple, robust and minimally intrusive boundary-scan testing of advanced digital networks which are not adequately addressed by existing standards. This includes AC-coupled networks, differential networks or both. This paper will describe the work that has been done thus far by the P1149.6 working group including: defects to be targeted by the proposed standard, physical layer implementation for both the driver and receiver, verification of proposed solutions through SPICE modeling, BSDL and tools implications. The paper will also discuss some of the challenges faced by the working group and will discuss new approaches taken on by the working group in the development of the proposed standard.