| 摘要 |
<p>The document file has a cover detachably secured over a stack of perforated sheets, there being an upright pin passed through holes in the latter and protruding above them. It is bent round a first coupling piece engaging together with it in a second one on the inside of the cover. The second piece is a rail running along the cover rear edge, so that the pin does not protrude through the cover. The first coupling piece (5) is shorter in the lengthwise direction than the second. Each protruding pin end (4) has its separate first coupling piece. These pieces are fitted at any desired intervals along the second.</p> |
