Iran and world powers reached a historic accord designed to prevent the Islamic Republic from developing nuclear weapons in return for ending sanctions that have crippled the nation’s economy and slashed its oil exports.

Here are some of the key elements of the agreement, according to a copy of the deal obtained by Bloomberg News and discussions with officials from one of the western delegations.

What are Iran’s main nuclear commitments?

Under the agreement, Iran reaffirms that it won’t develop or acquire nuclear weapons.

The United Nations atomic agency, or IAEA, will monitor and verify Iran’s compliance and provide regular updates to the UN Security Council. A joint commission consisting of Iran and the six world powers will also monitor the implementation of the accord.

Iran has agreed to eliminate 98 percent of its enriched uranium. It will dismantle two-thirds of of its enrichment capacity and forgo the possibility of making plutonium, a key component of a nuclear weapon.

The Islamic Republic, for 15 years, will carry out its uranium-enrichment activities exclusively at its Natanz facility, which will be under IAEA inspection. For the same period, it won’t keep any nuclear material at Fordow, a deep underground site which will be converted into a nuclear, physics and technology center.

Iran will also redesign and rebuild a modernized heavy-water research reactor at Arak, based on an agreed conceptual design, using fuel enrichment up to 3.67 percent. The facility was a central issue at the talks because plutonium recycled from a heavy-water reactor such as the one being built at Arak could be used to make powerful atomic weapons.

How will sanctions be removed?

Iran won’t receive any relief until it complies with the terms of the agreement, which could take months. Sanctions will remain in place until “implementation day,” after the IAEA confirms that the Islamic Republic has met commitments to curb its nuclear program.

What are the key sanctions to be lifted?

The UN Security Council will issue a resolution endorsing the accord, terminating all previous resolutions on Iran’s nuclear program. The European Union, simultaneously with Iran’s verified implementation of the accord, will end sanctions on industries including oil, natural gas, insurance and reinsurance.

The EU will also lift restrictions on access by Iranian banks to the Society for Worldwide Interbank Financial Telecommunication, known as SWIFT, a system used by banks to communicate transactions.

The U.S. agreed to stop its efforts to limit Iran’s oil sales and end restrictions on the six countries it allows to buy the country’s crude. The U.S. will also cease to apply sanctions on financial and banking transactions with Iranian banks and financial institutions. Restrictions on the sale of commercial passenger aircraft will also be lifted.

–With assistance from Jonathan Tirone in Vienna.