TIdIPMCastServer = class(TIdIPMCastBase);

TIdIPMCastServer is a TIdIPMCastBase descendant that implements an IP multicast server component using the UDP transport, as described in the Internet Standards documents: 

RFC 1112 - Host Extensions for IP Multicasting  

RFC 1458 - Requirements for Multicast Protocols  

TIdIPMCastServer implements abstract methods from the ancestor class, and provides additional methods and properties used for loopback diagnostics, setting socket options, and transmission of Multicast datagrams.