10 including a longitudinal tenon 26 and a vertical member 28 39 including a longitudinal mortise 30 the vertical member 28 39 of fig8 differs from the vertical member 28 of fig3 in that the two tenons 24 are not formed so that the total height of the vertical member 28 39 is equal to the length of the center strip 12 of the vertical member 10 the tenons 24 of the vertical member 12 are introduced into the associated recesses 20 of the lower left hand fig8 transverse member 8 the transverse member 8 having a horizontal orientation in fig8 is in flush contact with the contact surface 38 of the vertical member 28 39 the tenon 24 of an intermediate member 32 is introduced into the recess 20 39 of this transverse member 8 so that the compartment element 4 can be inserted between the intermediate member 32 and the vertical member 28 and the upper fig8 surface of the transverse member 8 fig9 shows a mounting table 44 which can be used for assembling the vertical members and transverse members 6 and 8 represented in fig3 to 5 this mounting table 44 is produced of square profiles as a coffered structure with longitudinal profiles 46 and transverse profiles 48 jointly forming a support grid for the strips of the members on the end portions of the transverse profiles 48 end parts 50 to 53 extending approximately in parallel with the longitudinal profiles 46 are formed these end parts include two stopper slats 54 56 extending at parallel spacing and in the longitudinal direction parallel to the longitudinal profile between which a space corresponding to the wall thickness of a center strip 12 is formed.