The injector system of the advanced photon source (APS) consists of a linac capable of producing 450-MeV positrons or greater than 650-MeV electrons, a positron accumulator ring (PAR), and a booster synchrotron designed to accelerate particles to 7 GeV. There are long periods of time when these machines are not required for filling the main storage ring and instead can be used for synchrotron radiation research. We describe here an extension of the linac beam transport called the low-energy undulator test line (LEUTL). The LEUTL will have a twofold purpose. The first is to fully characterize innovative, future generation undulators, some of which may prove difficult or impossible to measure by traditional techniques. Perhaps the most intriguing and exciting use of the LEUTL, however, will be in the planned investigation and generation of coherent radiation at wavelengths below 100 nm. This is due to the use of the high quality electron beam generated from a thermionic microwave gun.