BoF
while (! At_EoF) {
  Search("RH", NOERR+ERRBREAK)
  #103=CP
  Search("  ", NOERR+ERRBREAK)
  Reg_Copy_Block(103, #103, CP)
  if (File_Exist("|@(103)")) {
    // check files
    // <a href="ftp://updates.redhat.com/7.3/en/os/i386/kernel-2.4.20-28.7.i386.rpm">
    BoL 
    #104=Match("RH")!=0
    Ins_Text("  ", OVERWRITE*#104)
  } else {
    BoL 
    #104=Match("RH")!=0
    Ins_Text("x ", OVERWRITE*#104)
  }
  Line(1, NOERR)
}
BoF