Abstract: The fixture block is adapted to be combined with further correspondingly designed accessories with the aid of which workpieces to be machined can be brought into proper position or orientation for the particular machining operation, such as planing, milling, drilling and the like, and maintained in such proper position or orientation during at least one working cycle. The fixture block has horizontal and vertical contact surfaces designed as aligned rows of coplanar projecting areas separated by machined rows of coplanar recessed areas. The block is an L-shape body having a vertical leg and a horizontal leg, with the length and width of each leg being equal to each other and to the length and width, respectively, of the other leg, and with the thickness of each leg being equal to one-half its length or width. All surfaces of the block are formed with a plurality of tapped bores, and with smooth untapped bores of different diameters which at least partly intersect each other within the block.