When issuers of tokenized securities need guardrails around who can hold their tokens and where to send them, a four year-old Ethereum smart-contract framework called ERC-1404 comes into play.

That popular standard is now getting an upgrade.

Advisory firm Republic Crypto and token builder Upside have put together an enhanced version called ERC-1404 Prime that the two companies are betting on as a new foundation for issuing regulatorily compliant assets on the Ethereum blockchain.

The guardrails can be especially important for cryptos representing stock shares, real estate and other assets subject to complex investor rules. Issuers of these “security tokens” use ERC-1404 to ensure they don’t run afoul of the law by, for example, keep the tokens from getting transferred to investors who aren’t accredited or authorized.

Republic Head of Tokenization Jeff Vier said ERC-1404 Prime allows for more complex transfer restriction scenarios than the original standard. He said it prepares tokens for a world where centralized and decentralized finance might coalesce, perhaps through peer-to-peer swaps, which are a hallmark of decentralized exchanges.

“How do we improve for today with what regulators are looking for, what the industry is looking for, and also setting ourselves up to design assets that can exist in a future state?” he said. “That’s the way we're thinking about this.”

The new design can help tokens get to the secondary market faster, he said.

The enhanced version incorporates lessons learned in the four years since Tokensoft debuted ERC-1404, said Noah Thorp, CEO of Upside, a token issuance firm. Prime can handle automated lock-ups and dividend distributions, two features the original could not.

The original version of ERC-1404 takes the “simplest implementation possible that meets the regulatory requirements, Tokensoft CEO Mason Borda told CoinDesk.

“To date, we’re the only ones that have gotten SEC-registered tokens through the SEC on a public blockchain,” he said, referring to a treasuries-linked product on Ethereum.

Read more: 605 Days Later: How ArCoins Got the SEC Go-Ahead as an Ethereum-Traded Treasurys Fund