Abstract: The transport edges of a limited number of computer print sheets can be easily and manually torn off from a set or pile of form papers, especially the transporting margins of chain forms, having perforated margins provided with perforated holes engageable for paper transport. A desk clamping device consists of an oblong ruler shaped bottom bar, provided with one or more guiding stop elements to receive the perforated form margin, as well as another ruler shaped upper bar, being hingedly connected with the bottom bar. One longitudinal marginal side of the bottom bar can be moved in an upward direction, manually, this bottom bar being furthermore provided with means to bring the said longitudinal margin in a position opposite to and pressed against the bottom bar sharply and in a rectilinear way for locking such form margins simultaneously. Thereafter the form edges are torn off by means of a single tearing off movement, whereby the existing perforation or tearing line of the form sheet is followed.