The U.S. Commodity Futures Trading Commission (CFTC) published its final guidance on "actual delivery for digital assets" Tuesday, seemingly settling a longstanding question on when a cryptocurrency can be "delivered" from one party to another.

The CFTC shared a 35-page document stating that in its view, "actual delivery" occurs when a customer has complete control over the asset and the offeror no longer has any control over the asset by the end of 28 days after the transaction. The publication comes following several years of public input from exchanges and other stakeholders.

The regulator approved the draft on March 23, according to the document.

How "actual delivery" is defined has long been an open question. In 2016, law firm Steptoe & Johnson LLP petitioned the CFTC after the federal commodities regulator settled charges with crypto exchange Bitfinex on trading violation allegations.

The charges stemmed from CFTC allegations that Bitfinex maintained control over cryptocurrency private keys after delivering funds tied to margin trading, and therefore the funds weren't actually delivered. The charges were settled, with Bitfinex paying $75,000.