Defines the CCITT high level programming language CHILL (CCITT High Level Language) its language design and features: modes and classes, locations and their accesses, values and their operations, actions input and output, exceptions, handling time supervision, program structure, concurrent execution, general semantic properties and implementation options. Appendixes A-H includethe character set for CHILL, special symbols, special simple name strings, program examples, decommitted features, collected syntax, index of production rules and the index, respectively.