Scale like 1:100 and a length measured on the plan in mm—real-world meters.
Measured length on the drawing is in millimeters; the scale field is the denominator N in 1∶N (e.g. 50 for 1∶50). Real length in meters is (mm ÷ 1000) × N. Negative scales and zero are rejected.
Negative or zero scale denominators and non‑numeric drawing lengths are rejected.