Each prefix name has a symbol that is used in combination with the symbols for units of measure. For example, the symbol for "kilo-" is k, and is used to produce km, kg, and kW, which are the SI symbols for kilometre, kilogram, and kilowatt, respectively. Except for the early prefixes of "kilo-", "hecto-", and "deca-", the symbols for the multiplicative prefixes are uppercase letters, and those for the fractional prefixes are lowercase letters. There is a Unicode symbol for "micro" µ for use if the Greek letter μ is unavailable. When both are unavailable, the visually similar lowercase Latin letter u is commonly used instead. SI unit symbols are never italicised.