The coverage and depth of preferential treatment varies from one RTA to another. Modern RTAs, and not exclusively those linking the most developed economies, tend to go far beyond tariff-cutting exercises. They provide for increasingly complex regulations governing intra-trade (e.g. with respect to standards, safeguard provisions, customs administration, etc.) and they often also provide for a preferential regulatory framework for mutual services trade. The most sophisticated RTAs go beyond traditional trade policy mechanisms, to include regional rules on investment, competition, environment and labour.