TM and TE in CST Frequency Selective structures (FSS)

Just want to make sure I'm on the same page with CST. But, when using periodic boundary conditions, in the template for FSS, TM refers to p-polarization efield along x direction while TE refers to s-polarization E field along y direction? Where y and x directions are referenced to CST.
Also, when using wave guide ports, is it possible to set the polarization for TE and TM.
Thank you

for waveguide
yes,u can change polarization using option of waveguide port polarization to be 90 degree to change from TE to TM