need help about x25 protocol

hi everyone

here iam working with x25 protocol(dll),if any one have any idea about this protocol could u help me in the following querry.

actually in this x25 dll

Code:

---

x25data               
{               
OSINT        xd_len;        /* Length in bytes of xd_data */
char        xd_data[XD_DATALEN];        /* Data buffer address */
};

---

here is one of the method or function defined in that dll is x25xcall()

for that x25xcall() the following are the parameters.

Code:

---

public static extern unsafe int x25xcall(
                        int *Cid,                    /* connection id */
                        int X25NOWAIT,              /*waitmode flag*/
                        int iPort,                /*Portno of Eicon*/
                        int iInfo,                /*bit mask*/
                ref x25data sFacil ,          /*facility length and buffer*/
            ref x25data sUsage ,          /*userdata length and buffer*/
                        string Remote,            /*Remote DTE  address*/
                        string Local,              /*Local DTE  address*/
                        PostDelegate post,
                        IntPtr xi_ref);/

---

for this sfacil parameter,which values i have to pass.

please help me