To ensure that medical equipment, communications systems, and other electronics are protected from external electromagnetic interference (EMI) or that emissions from within the enclosure are contained. Measurement Procedure

The weak points are almost never the solid steel panels. The standard emphasizes testing around:

The EN 50147-1 standard offers several benefits to the railway industry:

The procedure involves measuring the signal level transmitted through the shield over a frequency range (typically 10 kHz to 40 GHz) and calculating the difference from a reference calibration.

If you are looking for the PDF, it is a copyrighted document usually available for purchase through official standards bodies rather than free public download. What is EN 50147-1?