In the case of units which are principally engaged in production, finance, insurance or redistribution, in respect of all their transactions except those relating to ownership of land and buildings, the following two cases may be distinguished:
(a) activity conducted exclusively on the economic territory of the country: units which carry out such activity are resident units of the country;
(b) activity conducted for a year or more on the economic territories of several countries: only that part of the unit which has a centre of economic interest on the economic territory of the country is deemed to be a resident unit. It may be:
1. either an institutional resident unit, whose activities conducted for a year or more in the rest of the world are excluded and treated separately (4), or
2. a notional resident unit, in respect of the activity conducted in the country for a year or more by a unit which is resident in another country.
