number e.g. 231-1002 (2=Hardware 3=Screw 1=Phillips then the unique number 1002) This is also more efficient for data entry where using numbers and dashes are part of a normal keypad which means you don't have to use both hands on a keyboard. One other bonus is that people usually understand numbers easier, and when you store products in a warehouse, you can put items in numerical order (for example, lower numbers at one end of an aisle, and as you continue, the numbers increase). Dash numbers There is a strong tradition in part numbering practice, in use across many corporations, to use suffixes consisting of a "dash" followed by a number comprising 1 or 2 digits (occasionally more). These suffixes are called dash numbers, and they are a common way of logically associating a set of detail parts or subassemblies that belong to a common assembly or part family. For example, the part numbers 12345-1, 12345-2, and 12345-3 are three different dash numbers of the same part family. In precise typographical and character encoding terms, it is actually a hyphen, not a dash, that is usually used; but the word "dash" is firmly established in the spoken and written usage of the engineering and manufacturing professions; "dash number", not "hyphen number", is the standard term. This comes from the era before computers, when most typographical laypeople did not need to differentiate the characters or glyphs precisely. Some companies follow a convention of circling the dash numbers on a drawing, such as in view designators and subpart callouts. Relationship of part numbers to drawing numbers Another widespread tradition is using the drawing number as the root (or stem) of the part number; in this tradition, the various dash-number parts usually appear as views on the self-same drawing. For example, drawing number 12345 may show an assembly, P/N 12345-1, which comprises detail parts -2 ("dash two"), -3, -4, -8, and -11. Even drawings for which there is currently only one part definition existing will often designate that part with a part number comprising drawing number plus -1 ("dash one"). This is to provide extensibility of the part numbering system, in anticipation of a day when it might be desired to add another part definition to the family, which can then become -2 ("dash two"), followed by -3 ("dash three"), and so on. Some corporations make no attempt to encode part numbers and