Chapter 6 studies the substantive meta-rules of the TBT Code of Good Practice. As the Appellate Body never provided interpretive guidance over these provisions, how to apply them to standards and VSS remains unclear. Chapter 6 analyses crucial TBT principles providing that standards do not discriminate, do not create unnecessary barriers to trade and are based on relevant international standards. The interpretation of similar TBT provisions concerning technical regulations is used as guidance in understanding the transposition of these obligations and in suggesting how these legal tests are applicable to VSS. The chapter acknowledges the peculiar nature of standards identifying products with distinct quality features such as VSS. It identifies relevant differences from technical standards that must be taken into account for interpretive purposes. These include the objectives pursued by a scheme that can be accepted as legitimate, the implications of the treatment-no-less-favourable standard on measures that structurally distort competitive opportunities and whether the detrimental impact generated stems exclusively from a legitimate regulatory distinction.