if ($mode == MODE_GETNEXT) {

check if the OID < ROOT OID.1.0 

  set the OID to ROOT OID.1.0 
  return the value of ROOT OID.1.0

check if the OID == ROOT OID.1.0
  set the OID to ROOT OID.2.0 # Next request
  return the value of ROOT OID.1.0


.
.
.