Romanization of Greek Greek numerals which employed the entire alphabet, including the nonstandard letters digamma, stigma, or sigma-tau (placed between epsilon and zeta), koppa (placed between pi and rho), and sampi (placed after omega). As revised in 2001, ELOT 743 provides for the uncommon characters to be given (in Greek) as $ for stigma, + for koppa, and / for sampi. These symbols are not given lower-case equivalents. When used as numbers, the letters are used in combination with the upper "keraia" numeral sign ⟨ʹ⟩ to denote numbers from 1 to 900 and in combination with the lower "keraia" ⟨͵⟩ to denote multiples
Mu (letter) monotonic orthography, the ancient version is written with an acute accent instead of a circumflex: . The lowercase letter mu (μ) is used as a special symbol in many academic fields. Uppercase mu is not used, because it appears identical to Latin M. "μ" is conventionally used to denote certain things; however, any Greek letter or other symbol may be used freely as a variable name. In classical physics and engineering: In particle physics: In thermodynamics: In evolutionary algorithms: In type theory: In chemistry: In biology: In pharmacology: In orbital mechanics: The Olympus Corporation manufactures a series of digital cameras