Exchange of information and assistance in collection: mutual definitions frame tax information exchange and collection assistance obligations. Article 4 defines key terms for the Brunei-India tax cooperation agreement: territorial scope, persons and companies, publicly traded companies and recognised stock exchanges, collective investment funds, the concept of tax, competent authorities, requesting and requested Parties, and the meanings of 'information', 'information gathering measures' and 'assistance in collection measures'. It further provides that undefined terms derive their meaning from each Party's domestic law at the relevant time, with tax-law meanings prevailing unless the context or mutual agreement under Article 11 provides otherwise.