Abstract: This invention comprises a display especially suitable for a large system, such as a utility distribution network diagram, a map, or the like, which is subject to frequent revision. The complete display is made up of a multiplicity of small display members arranged in abutting relationship, which can be revised and replaced individually as necessary to keep the entire display up-to-date, without the necessity of replacing the complete display. A frame having an array of apertures, each smaller than one display member, supports the entire display. Each display member has attached to its back at least one mounting unit which is removably receivable in one of the apertures in the frame.