What do the column headers for bolt design value tables 11 A-K in the NDS mean?

• The first, Z_||, is for main and side members loaded in the same direction parallel to grain.
  The second, Z_s⊥, is for a side member loaded perpendicular to grain and the main member loaded parallel to grain.
  The third, Z_m⊥, is for a main member loaded perpendicular to grain and the side member loaded parallel to grain.
  The fourth, Z_⊥, is for main and side members loaded perpendicular to grain.
  
  Click on the following to see an illustration of each loading condition:
  Parallel to grain in all members, (Z_||)
  Parallel to grain loading in side, perpendicular in main, (Z_m⊥)
  Perpendicular to grain in side, parallel to grain in main, (Z_s⊥)
  Perpendicular to grain loading in all members, (Z_⊥)