The Uniform Customs and Practice for Documentary Credits ("UCP") may be treated as a useful laboratory for studying the scope and limitations of self regulation. This is due to its almost universal success on a global stage which provides it a perspective rarely available for self regulatory provisions and due to extensive experience of judicial review of it. In this sense, it is worthwhile to examine in brief the latest iteration of the UCP, Publication No. 600 ("UCP600"). This article describes and analyze some of core provisions of the UCP600 from the perspective of their adequacy as an exercise in self regulation. It is attempted first in view of several categories of private rulemaking; definitional rulemaking, default rules, procedural rules, and remedies. After that, it is examined second in view of sound rulemaking which is related to the relative role of law and practice. It points out rich and varied insights into the possibilities and problems associated with private rulemaking in connection with commercial transactions.