property Bindings: TIdSocketHandles;

Bindings is a TIdSocketHandles property and a collection of TIdSocketHandle instances. For TIdUDPServer, Bindings will contain TIdSocketHandles instances with an allocated socket type of ID_SOCK_DGRAM. 

Bindings provides the DefaultPort number for the TIdUDPServer and is used by the TIdUDPListenerThread to gain access to the socket handle and low-level access methods provided by the protocol stack. 

Use Bindings to create socket bindings for servers with multiple network adapters (Host addresses), or which listen on multiple Port numbers.