Abstract: An easily assembled and dis-assembled knockdown EMI/RFI shielded electronic rack enclosure incorporating the structurally cooperative use of squaring bracket assemblies for the squared unitized corner joining of adjacent vertical side wall frame to horizontal top and bottom frame components and thereby substantially eliminate the distortion effects of racking forces, as well as the use of joining clamps for the unitized assembly connection of top and bottom enclosement panel components respectively to the opposing side enclosement panel components and thereby additionally substantially eliminate EMI/RFI shielding leaks resultant from mechanical shock forces.