Boundary information for periodic structures

[fredrikekre]

Hi, I am trying to output which faces are external boundaries when generating periodic structures. I have played around with the -faset and the -nset options, but no success so far. Is there a way to output this information?
For example:

neper -T -n 2 -periodicity all
neper -M -format inp n2-id1.tess

gives empty sets regarding the boundary.