1306579 Filing papers; indexing OPTISCHE INDUSTRIE "DE OUDE DELFT" NV 8 July 1971 [28 July 1970] 32132/71 Heading B6E A loose-leaf folder comprises a first transparent plastics envelope 1, Fig. 1, containing a second opaque envelope 2 in turn containing loose-leaves 3, the second envelope being provided along a vertically disposable edge with a photo-electrically readable black and white code 4 identifying the contents of the envelope 2. The code- 4 may be projected to the reader (not shown) by a reflector 5 fixed on the envelope 1 and juxtaposed over the code 4. The reflector 5, Fig. 3, which may be a transparent plastics strip, has an inclined code reflecting surface 6 opposite which is disposed a magnifying surface 7. The reflector may be integral with or attached to the envelope 1 or may be constituted by an inclined code reflecting metallic strip. In an embodiment (Fig. 2, not shown) a pair of folders (8,8<SP>1</SP>) may be filed contiguously between upper and lower racks (10, 11) of a frame and the reflectors (9, 9<SP>1</SP>) which do not extend over more than half the length of the edges are attached to facing opposite sides of the envelopes such that the reflectors extend in pairs along common vertical lines.