;F.601; quality of service. F.710-F.730 F.400-F.422; Message handling and directory services - operations and definition F.500 service. III.1 G.101-G.181 XILXV General characteristics of international telephone connections and circuits. III.2 G.211-G.544 International analogue carrier systems. III.3 G.601-G.654 Transmission media - characteristics. III.4 G.700-G.772 XV; XVIII General aspects of digital transmission systems; terminal equipments. III.5 G.801-G.956 XV; XVIII Digital networks; digital sections and sigital line systems. III.6 H and J Line transmission of non-telephone signals. Transmission of sound- programme and television signals. III.7 1.110-1.257 XVIII Integrated Services Digital Network (ISDN) - general structure and service capabilities. III.8 1.310-1.470 XVIII Integrated Services Digital Network (ISDN) overall network aspects and functions; ISDN user-network interfaces. III.9 1.500-1.600 XVIII Integrated Services Digital Network (ISDN) - internetwork interfaces and maintenance principles. M.10-M.782 General maintenance principles: maintenance of international transmission systems and telephone circuits. M.800-M.1375 Maintenance of international telegraph; phototelegraph and leased circuits. Maintenance of the international public telephone network. Maintenance of maritime satellite and data transmission systems. Maintenance of international sound-programme and television transmission circuits. Specifications for measuring equipment. Telephone transmission quality. Series P Recommendations. Q.1-Q.118bis General Recommendations on telephone switching and signalling. Functions and information flows in the ISDN. Supplements. Q1.20-Q.180 Specifications of Signalling Systems Nos. 4 and 5. Q.251-Q.300 Specifications of Signalling System No. 6. Q.310-Q.490 Specifications of Signalling Systems R1 and R2 (Study XI). Q.500-Q.554 Digital local transit combined and international exchanges in integrated digital networks and mixed analogue-digital networks. Supplements International standards organisations 22