"Control of an asset," as it's defined under IFRS 15, refers to the ability to direct the use of, and obtain substantially all of the remaining benefits from, the asset. This concept is fundamental to the recognition of revenue, as revenue is recognized when a customer obtains control of a promised good or service.

Here's a more detailed understanding of control:

1. Directing the Use of the Asset: This implies that the customer has the ability to direct the use of that good or service. For example, if a customer purchases a car, they have control over that car and can decide how and when to use it.
2. Obtaining Benefits from the Asset: This means that the customer has the ability to obtain the potential cash inflows (or reduce the cash outflows) that are directly attributed to that good or service. For example, if a business purchases a machine, it will obtain the benefits by using that machine to produce goods that can be sold for cash inflows.
3. The Asset: An asset is any resource that is capable of producing economic benefits. Under IFRS 15, an asset could be a physical good, right, or service.
4. Control Transfer: Control is considered to be transferred when the customer has the ability to direct the use of, and obtain substantially all of the remaining benefits from, the asset and the customer has accepted the asset.
5. Indicators of Control: Some indicators that a customer has obtained control of a good or service can include the entity having a right to payment for the asset, the customer having legal title to the asset, the entity having transferred physical possession of the asset, the customer having the significant risks and rewards of ownership of the asset, and the customer having accepted the asset.

In summary, the concept of control is a key determinant of when revenue is recognized under IFRS 15. It requires judgement to assess and can significantly affect the timing and amount of revenue recognized.