Abstract: A file folder includes a rail member fixed to the connection portion of the file folder and the rail member includes a plurality of ribs extending from a surface thereof so as to define grooves between the ribs. The grooves communicate with openings in a top end and a lower end of the rail member. Each rib has a head on a distal end thereof and the head is wider than a width of the rib so as to form a narrow entrance corresponding to each groove. A holding unit has an elongate insertion which includes an enlarged ridge on a side thereof so as to be slidably inserted into the grooves via the openings and the insertion is sized to be slidably engaged with the narrow entrance. Document is positioned or collected by the holding unit.