Boundary conditions for open and closed strings

Hi,



I am a bit confused about the terminology used for the boundary conditions describing open and closed strings.



For the open string,



Ramond case: [itex]\psi^+(\sigma = \pi, t) = \psi^-(\sigma = \pi, t)[/itex]

Neveu-Schwarz case: [itex]\psi^+(\sigma = \pi, t) = -\psi^-(\sigma = \pi, t)[/itex]



Question 1: Is it correct that the "R sector" refers to the Ramond case, and the "NS sector" refers to the Neveu-Schwarz case?



For the closed string,



Ramond case: [itex]\psi^+(\sigma = 0) = \psi^+(\sigma = \pi)[/itex], [itex]\psi^+(\sigma = 0) = \psi^-(\sigma = \pi)[/itex]



Neveu-Schwarz case: [itex]\psi^+(\sigma = 0) = \psi^+(\sigma = \pi)[/itex], [itex]\psi^+(\sigma = 0) = -\psi^-(\sigma = \pi)[/itex]



Question 2: So,



NS-NS means both [itex]\psi^+[/itex] and [itex]\psi^-[/itex] are antiperiodic

NS-R means [itex]\psi^+[/itex] is antiperiodic and [itex]\psi^-[/itex] is periodic

R-NS means [itex]\psi^-[/itex] is antiperiodic and [itex]\psi^+[/itex] is periodic

R-R means [itex]\psi^+[/itex] is periodic and [itex]\psi^-[/itex] is periodic?



I apologize for the triviality of these questions but the classification of the 4 sectors is confusing me a little...



I'd appreciate some help.