(computing) Any character used to specify a function of a piece of software or hardware (such as carriage return of a printer)

(business, espionage, military) A name used to clandestinely identify somebody or something, either for military or espionage purposes, or for commercial confidentiality.

(British spelling) Any system where colours are used to categorize elements of sets.

(British spelling) To mark items with a colour code as a means of sorting.

(computer science) A system of instructions and data directly understandable by a computer's central processing unit.

Any code whose elements may take one of three values

Non-redundant software code comprising of focussed task-specific modules and functions, written in a systematic manner so that another coder can easily interpret or modify it.

(business) An account designator, especially one that is not purely numeric.

A set of rules dictating acceptable behaviour and decisions in a specified environment.

(US) A postal code, especially for addresses served by the US Postal Service, consisting of a five- or nine-figure number. / (US, by extension) Any postal code.