TOPIC:

string lastATA = String.Empty;

public object DoWork()
{
  string ata = (String)InValues[0].GetString();
  if (ata != null)
  {
    if( IsNumeric(ata) )
    {
      lastATA = ata;
      return ""; // we want to filter the first group header row!
    }    
  }

  return lastATA;
}

private bool IsNumeric(string s)
{
  int i;

  if (Int32.TryParse(s, out i))
    return true;

  return false;
}

string [] sConditions = null;

public object DoWork()
{
  // Load conditions only first time
  if (sConditions == null)
  {
    sConditions = File.ReadAllLines("conditions.txt");
  }

  // get the first input parameter
  string sCmp = (string)InValues[0].GetString();
  if (sCmp == null)
    return true;

  // check all conditions
  foreach(string cond in sConditions)
  {
    if (sCmp == cond)
      return false; // false = no filter, pass this line
  }

  return true; // true = Filter this line
}