It's brokers' turn for crypto clarity in the U.S. Securities and Exchange Commission's series of staff statements meant to reveal its current thinking on how to treat the digital assets space, in this case touching on brokers' "physical possession" of assets and separately posing some questions about so-called alternative trading systems (ATSs) for crypto.

One of the two latest releases this week deals with custody of customers' crypto securities at regulated broker-dealers, advising the firms on how to properly possess those assets, including protecting customers' private keys. As long as they follow the informal standards set out in the statement, broker-dealers won't get a knock on their door from the SEC.

Their approach must also anticipate "blockchain malfunctions, 51% attacks, hard forks, or airdrop," according to the statement from the SEC's Division of Trading and Markets.

The agency's advice could help traditional trading firms find further comfort in their handling of crypto assets. It would include tokenized stocks and debt securities, though the specific definition of a crypto security hasn't yet been fully established.

The SEC's series of crypto statements have been greeted with open arms by the industry, but they don't have the authority of rulemaking or guidance, so they'd be easy to reverse if the agency leadership were to change hands.

Also this week, the U.S. securities regulator issued a "frequently asked questions" document delving into activity at crypto ATS. As pointed out by Commissioner Hester Peirce, who heads the agency's crypto task force, the questions focus largely on trading and settlement.

"Trading platforms and market participants need to be able to operate under the certainty of clear market structure rules that facilitate fair and orderly markets without imposing unnecessary burdens," Peirce said in a statement.

Read More: U.S. SEC Chief Atkins Says Clarity Coming on Crypto Tied to Investment Contracts