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].