I don't understand why there are 2 dashed values in this table: http://en.wikipedia.org/wiki/Quantum_number#Quantum_numbers_with_spin-orbit_interaction. I have that [itex]j=l+s,l+s-1,...,|l-s|[/itex]. So let's take #1 of the table. They give l=1 and we know that [itex]s=1/2[/itex]. Thus [itex]j=l+s=3/2[/itex] or [itex]j=l-s=1/2[/itex]. Why is l-s=1/2 dashed?! The same question appears for #6.