Table:
|  | Year-ended 31 March 2019 | Year-ended 31 March 2018 Restated See note 2 |
| --- | --- | --- |
|  | $M | $M |
| Revenue | 710.6 | 639.0 |
| Net deferral of revenue (see note 23) | 49.7 | 129.6 |
| Billings | 760.3 | 768.6 |
| Currency revaluation | 25.9 | 18.7 |
| Constant currency billings | 786.2 | 787.3 |
Paragraphs:
Billings
Billings represent the value of products and services invoiced to customers after receiving a purchase order from the customer and delivering products and services to them, or for which there is no right to a refund. Billings do not equate to statutory revenue.
Question:
What were the components in the table used to calculate Billings?
Answer: Revenue, Net deferral of revenue