specification, protocol (FDT) A formal method for

developing telecomunications services and protocols. FDTs

range from abstract to implementation-oriented descriptions.

All FDTs offer the means for producing unambiguous

descriptions of OSI services and protocols in a more

precise and comprehensive way than natural language

descriptions. They provide a foundation for analysis and

verification of a description. The target of analysis and

verification may vary from abstract properties to concrete

properties. Natural language descriptions remain an essential

adjunct to formal description, enabling an unfarmiliar reader

to gain rapid insight into the structure and function of

services and protocols.