For the purposes of this Regulation, the following definitions apply:

(1) "activity data" means the data on the amount of fuels or materials consumed or produced by a process as relevant for the calculation-based monitoring methodology, expressed in terajoules, mass in tonnes, or for gases as volume in normal cubic metres, as appropriate;

(2) "trading period" means an eight-year period referred to in Article 13(1) of Directive 2003/87/EC;

(3) "tonne-kilometre" means a tonne of payload carried a distance of one kilometre;

(4) "source stream" means any of the following: (a) a specific fuel type, raw material or product giving rise to emissions of relevant greenhouse gases at one or more emission sources as a result of its consumption or production; (b) a specific fuel type, raw material or product containing carbon and included in the calculation of greenhouse gas emissions using a mass balance methodology;