Financial regulators on Wednesday unveiled a plan for one of the last remaining major Dodd-Frank Act rules, approving a 300-page proposal that would define exactly what constitutes a swap and which agency -- the Securities and Exchange Commission or the Commodity Futures Trading Commission -- will regulate what types.

Both agencies voted to issue the proposal and seek comment jointly. While the SEC acted unanimously, Republican CFTC Commissioner Jill Sommers opposed the proposed rule.

The CFTC also proposed rules setting new capital requirements for swap dealers and major swap participants; new minimum requirements for how futures merchants have to keep and protect customers' collateral for swaps deals; and a rule that requires dealers to make audio recordings of transactions.

One part of the rules would force clearinghouses to maintain "total legal separation" of customer's collateral, preventing them from seizing the collateral of one trader to cover the margin losses of another.

All of the rules had been anxiously awaited, as regulators' determination of exactly what constitutes a swap has been key to a host of companies, dealers, industries and exchanges understanding the Dodd-Frank Act's eventual impact on their businesses. One major part of the Dodd-Frank Act extended government regulation of financial products to previously unregulated swap or derivative transactions.

Until Wednesday, while regulators proposed requirements for those engaging in derivative or swap trades, it wasn't fully clear exactly who would be covered.

The regulators' proposal divides swaps into three general categories. Those that are securities-based would be regulated by the SEC. Those not securities-based would be regulated by the CFTC. And regulators on Wednesday said they will have a process for those that are combinations and may need legal opinions to determine who regulates them.

The agencies offered a number of clarifications. Narrow securities-based indexes including indexes where there is discretion to change the composition or weighting would be overseen by the SEC, while broader indexes would generally be overseen by the CFTC.

The agencies also moved to exclude a number of transactions that might be viewed as swaps.

Insurance contracts made by companies or individuals for their own benefit and commercial transactions such as leases, mortgages and commercial loans -- even those tied to a price index -- would be exempt. Also exempt would be consumer-related activities such as contracts for home heating oil and mortgage rate locks.

That still leaves plenty of new areas where swaps will now be subject to government regulation.

Besides the regular swaps, CFTC moved to classify swaps done in attempts to evade some of the impact of Dodd-Frank and without any business purpose as swaps that would be regulated. Sommers in her dissent characterized the move as "overreaching."

The CFTC proposed a rule on minimum capital requirements for swap dealers and swap recipients that would apply to swap dealers or major swap participants who aren't otherwise regulated by the government.

They would have to have at least $20 million in capital, and the number could be larger depending on a variety of factors. In some cases, the capital requirement could be the same as regulators require for bank holding companies.

In a third rule, the CFTC moved to require better protection of collateral to swaps and the question of whether collateral could be commingled in determining whether a trader has enough collateral on hand.

While the CFTC and the SEC agreed on most issues, they had differing views on several, including whether insurance for swaps itself amounted to a swap and asked questions about that.