Generally used in Nanotechnology, the nanometre or nanometer (American spelling) is a unit of length in the metric system, equal to one billionth of a metre. As per the international System of Units (SI), the standard symbol for the nanometer is nm. The name combines the SI prefix nano- (dwarf) with the parent unit name metre (unit of measurement). In scientific notation, it can be written in as 1×10−9 m, in engineering notation as 1 E−9 m, and is simply 1 / 1,000,000,000 m. One nanometre equals ten angstroms. The nanometre is often used to express dimensions on an atomic scale. The nanometre was formerly known as the millimicrometre or millimicron, commonly, since it is 1/1000 of a micron (micrometre), and was often denoted by the symbol mµ or (more rarely) µµ. In 1960, the U.S. National Bureau of Standards adopted the prefix "nano-" for "a billionth". The nanometre is often associated with the field of nanotechnology. Since the late 1980s, it has also been used to describe generations of the manufacturing technology in the semiconductor industry.