H ELECTRICITY
H04 ELECTRIC COMMUNICATION TECHNIQUE
H04L TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
H04L12/00 Data switching networks
H04L12/16 Arrangements for providing special services to substations
H04L12/18 for broadcast or conference; , e.g. multicast
H04L12/1813 for computer conferences, e.g. chat rooms
H04L12/1827 Network arrangements for conference optimisation or adaptation