"NS" should read "Nominal Size." It determines overall size of the elbow. E.G. a Long Radius 8" NS elbow is 12" long from CL of inlet to CL of outlet, despite having an OD of 8.625". I'm not thoroughly familiar with metric piping, as long as NS•Elbow Radius = CL to CL dimensions of the fitting, the dimensions will work out. The spreadsheet is otherwise blind to units. Use mm, cm, in, ft, km, etc, as long as you're consistent.

Offset pushes the branch left (-) and right (+) from this view.

L branch (CL-Base) should be read as "Length of branch connection from base to extrados along the branch centerline."

L branch (Outer Edge-Base) should be read as "Length of branch connection from base to extrados along the longest edge of the branch."

L branch (inner Edge-Base) should be read as "Length of branch connection from base to extrados along the shortest edge of the branch."

Elevation of the horizontal pipe minus "K" is this spreadsheet's input "L". Note again, that "L" must be same units as NS and OD, if you modify this input to be the difference of elevations.