Documentation for current Requirement (Emissions) :
Version B of the requirement is a refinement of version 001 with the added detail of an effective year, 2016, presumably because that is when a new set of limits takes effect. In the second step of the scenario this version of the requirement replaces version A, but the variant expression only specifies the ULEV option. In the next step of the scenario the variant expression is changed to further qualify this requirement for the US market.