Code:
raw 332:*:{ set %T2 To: $3- } 
raw 333:*:{ 
  if (!$read(topics.txt,nw,$+($2 Topic was set by $3 on $Date(ddd. mmm. dd yyyy)) %T2)) { write topics.txt $+($2 Topic was set by $3 on $Date(ddd. mmm. dd yyyy)) %T2 }
}