The LayGO Application Programming Interface (API) gives programs the ability to use LayGO communications services. These services include control of synchronous communications hardware and use of data communications protocols such as X.25 and Frame Relay.

This manual explains how to use LayGO API to setup the LayGO protocol stack and to allocate, configure, and use LayGO protocol services.

The Overview section explains LayGO's modular design, lists the benefits of developing with LayGO, introduces the OSI model, explains the concept of state machines and state tables and gives a summary of the LayGO API functions.

The API Services section explains the API state machine and how to access and use services provided by the LayGO API.

Appendix A gives details of the CCITT X.25 Packet Level State Machine.

Appendix B is a glossary of terms frequently used in data communication.

Appendix C is a list of recommended reference material and standards.