A Pascal extension for formal specification of computer network protocols. Protocols are described by modules which are communicating NFAs. Modules are arranged in a dynamic hierarchy and communicate at named interaction points.

EstPC Compiles Estelle into C. petdingo Translates Estelle into C++

Adopted by ITU-T. ISO 9074 (1989).

["The Formal Description Technique Estelle", M. Diaz et al eds, N-H 1989].