This display was developed by Arturo de Ascanio in the late 1960s. At that time the spread was described while the packet was held by its sides. Closely related is Roger Smith's K.S. Display, published in his Smith on Cards 2: The K-S Control System, 1971, p. 1. Smith's spread display sequence used only the milking action to remove the top and bottom cards of the packet, which he felt distinguished it sufficiently from the Ascanio Spread, which at the time was circulating among card magicians but had not yet been published in English. In Smith's K.S. Display, the packet is held by the ends rather than by the sides, which is the grip that quickly became the preferred one for the Ascanio Spread when it became better known in the U.S. Ascanio had explored this grip for his display as well. For further history on this sleight and how it came to be published in the English literature, see The Ascanio Spread by Jon Racherbaumer, 1976.
As a sidelight, note Max Katz's M. K. Thumb Break Count in Hugard's Magic Monthly, Vol. 15 No. 4, Sep. 1957, p. 37. This false-display spread is a transitional technique between the Buckle and Pull-down Counts and Ascanio's spread. Katz combined a back spread with a thumb break to keep two or more cards squared as one below the top card of the spread.