drawing numbers with common encoding; they are paired arbitrarily. Parametric families of parts, and tabulations of part numbers with parameter values Often more than one version of a part design will be specified on one drawing. This allows for easy updating of one drawing that covers a family of parts, and it keeps the specifications for similar parts on one drawing. For example: A common application of tabulation of part families is multiple dimensions within a general design, e.g. bushing: Design modification suffixes It is a common concept in many corporations to add certain suffixes beyond, or in place of, the regular dash numbers, in order to designate a part that is mostly in conformance with the part design (that is, mostly "to print"), but intentionally lacks certain features. The suffixes are usually "intelligent", that is, they use an encoding system, although the encoding systems are usually corporation-specific (and thus cryptic, and of little use, to outsiders). An example of such a design modification suffix is adding "V" or "Z" to the end of the part number to designate the variant of the part that is purchased "less paint", "less plating", "with the holes not yet drilled", "intentionally oversize by ", or any of countless other modifications. The intent is usually that the feature in question (such as holes not yet drilled, or paint not yet sprayed) will be added at a higher assembly level; or that maintenance workers in the field will choose from a kit of undersize and oversize parts (such as bushings) in order to achieve a certain fit (sliding fit, light press fit, etc.). Sometimes the terms "engineering part number" and "manufacturing part number" are used to differentiate the "normal" or "basic" part number (engineering PN) from the modification-suffixed part number (manufacturing PN). Symmetrical parts Many assemblies with reflection symmetry, such as the fuselages and wings of aircraft, the hulls of ships and boats, and the bodies of cars and trucks, require matched pairs of parts that are identical, or nearly identical, except for being mirror images of each other. (For example, the left and right wings of an airplane, or the left and right fenders or doors of a car.) Often these related parts are designated left-hand (LH) and right-hand (RH) parts. It is a common practice to give them sequential dash numbers, or -LH and -RH part number suffixes. It is also not uncommon