typedef struct t_vpi_systf_data {
  PLI_INT32 type;     // vpiSysTask, vpiSysFunc 
  PLI_INT32 sysfunctype; // vpiSysTask, vpi[Int,Real,Time,Sized, SizedSigned]Func 
  PLI_BYTE8 *tfname;  // First character must be `$' 
  PLI_INT32 (*calltf)(PLI_BYTE8 *);
  PLI_INT32 (*compiletf)(PLI_BYTE8 *);
  PLI_INT32 (*sizetf)(PLI_BYTE8 *); // For sized function callbacks only 
  PLI_BYTE8 *user_data;
} s_vpi_systf_data, *p_vpi_systf_data;