HS X.25 is a software library in C (supplied with full source code) which implements ITU-T recommendation X.25 - Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit. Includes HsDL (Data Link) and HsSock (Winsock interface) for X.25 over IP applications (XOT))