This text investigates the technical standards and operational protocols governing X-series data communications networks. Uyless D. Black, an established authority in computer communications, provides a structured analysis of the CCITT (now ITU-T) standards. The book utilizes technical specifications and architectural diagrams to explain how data packets are routed, managed, and verified across international network infrastructures.

Experts recognize this work as a foundational reference for understanding the evolution of packet-switched network architecture. Readers frequently note the technical density of the prose, which is intended for network engineers and students of telecommunications history.