A distinction is made between symbols and characters. Characters, standing only for themselves, may be used in strings or as literal constants. Apart from such occurrences, a program may be regarded as a sequence of symbols, each visibly representable by a unique character or combination of characters. The symbols of the language are defined (see Appendix B), but the characters are not. For the purpose of the language definition, words in upper case letters are treated as single symbols. Lower case letters are reserved for use in identifiers, which may also include digits in non-leading positions. Except where they are used as strings, layout characters are ignored by a Coral 66 compiler.
A program is made up of symbols (such as BEGIN, =, 4) and arbitrary identifiers which, by declaration, specification or setting acquire the status of single symbols. Identifiers are names referring to objects which are classified as
data (numbers, arrays of numbers, tables)
places (labels and switches)
procedures (functions and processes)