Abstract: A shroud segment adapted to mount to the casing of the turbine or compressor of a gas turbine engine includes opposed ends, an inner face, an outer face and forward and aft side mounting rails. The forward and aft side mounting rails are each formed with a pair of substantially T-shaped relief slots having a straight stem section extending inwardly from the outer face of the shroud body toward the inner face, and an arcuate-shaped head section connected to the stem section which reduces stress concentrations at the base of the stem section of the relief slot.