Identifier

1. In telecommunications and data processing systems, one or more characters used to identify, name, or characterize the nature, properties, or contents of a set of data elements.

2. A string of bits or characters that names an entity, such as a program, device, or system, in order that other entities can call that entity.

3. In programming languages, a lexical unit that names a language object, such as a variable, array, record, label, or procedure.

Note: An identifier is placed in a label. The label is attached to, is a part of, or remains associated with, the information it identifies. If the label becomes disassociated from the information it identifies, the information may not be accessible.

Source: from Federal Standard 1037C