A Pascal extension for formal specification of computer networkprotocols. 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].