Article 5 of the OECD Model Tax Convention on Income and on Capital deals with the definition of permanent establishment.
Working Party 1 on Tax Conventions and Related Questions - which is the subgroup of the OECD Committee on Fiscal Affairs in charge of the OECD Model Tax Convention - has recently undertaken work on the Commentary on Article 5 to develop an alternative provision on activities in connection with the exploration and exploitation of extractible natural resources, together with related commentary.