title: Normalization of an 1:1 or 1:0 relationship
body: <p>when using relation databases and you want 3NF (do you call it 3NF in english?), then you pull 1:1 relationsships together into one table. But what happens if the rationship is 1:0/1 (/ meaning or)?</p>
  
  <p>Then you keep them separated to avoid blank spaces in tables? Kepping them apart is valid 3NF in ths case?</p>