Abstract: A fenestration unit such as a door operable in a sliding mode and a bi-fold folding mode. Examples include a frame, a first panel, a second panel, and one or more fold hinges releasably pivotally connecting a second side portion of the first panel to a first side portion of the second panel and defining a folding axis. In the sliding mode (1) the fold hinges are configured to disconnect the first and second panels, (2) the first panel is in a closed position with respect to the frame, and (3) the second panel is configured to slide along a path generally parallel to the first panel between a closed position and a sliding open position.