tokens: Electrical cable assemblies shall simulate actual installation and usage . NOTE 1 Proper construction techniques such as use of twisted pairs , shielding , and shield terminations are determinant features . NOTE 2 Details on the cable construction used for testing are defined in the EMEVP DRD of ECSS - E - ST-20 , and maintained in the EMEVR DRD of ECSS - E - ST-20 .