13.6. Revenue from contracts with customers by duration of contract
| NOTE | Refining Segment |
Petrochemical Segment | Energy Segment | Retail Segment |
Upstream Segment | Corporate Functions | Total | ||||||||
| 2021 | 2020 | 2021 | 2020 | 2021 | 2020 | 2021 | 2020 | 2021 | 2020 | 2021 | 2020 | 2021 | 2020 | ||
| Short-term | 56 925 | 33 941 | 16 003 | 10 580 | 14 719 | 8 983 | 40 845 | 30 620 | 797 | 482 | 419 | 62 | 129 708 | 84 668 | |
| Long-term | 24 | 132 | – | – | 1 286 | 1 108 | – | 4 | – | – | 1 | 3 | 1 311 | 1 247 | |
| 13.1 | 56 949 | 34 073 | 16 003 | 10 580 | 16 005 | 10 091 | 40 845 | 30 624 | 797 | 482 | 420 | 65 | 131 019 | 85 915 | |
The duration of most contracts within the Group is short-term. Revenues on services for which start and end dates fall in different reporting periods are recognised according to the degree of complete fulfilment of the performance obligation using the input-based method. Contracts that remain unfulfilled in full as at the balance sheet date relate to i.a. construction and installation contracts.
As at 31 December 2021 the Group analysed the value of the transaction price allocated to unfulfilled performance obligations.
The unfulfilled or partially unfulfilled performance obligations as at 31 December 2021 mainly concerned contracts for the sale of electricity and power media and for the supply of newspapers, subscriptions, advertising broadcast, parcel delivery and collection services that will end within 2022 or are concluded for an indefinite period with a notice period of up to 12 months.
Due to the fact that the described performance obligations are part of the contracts, that can be considered short-term, or the revenues from fulfilled performance obligation under these contracts are recognised in the amount that the Group has the right to invoice, the Group applied a practical solution, according to which it does not disclose information about the total amount of the transaction price allocated to the performance obligation.