UNITED NATIONS -- U.N. Security Council members approved a resolution Friday outlining a peace process for Syria involving talks by representatives of the Damascus government and the opposition, but the draft says nothing on the critical issue of what role President Bashar Assad will play.

The resolution acknowledges that the peace process will not end the conflict because it bars "terrorist groups" operating in the country, including the Islamic State of Iraq and Syria (ISIS) and al-Nusra Front, from participating in a cease-fire.

CBS News' Pamela Falk reported the vote in favor of a plan was a rare showing of unity in the U.N. Security Council, which came together the day before on a resolution to prevent the flow of funds to ISIS.

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Secretary of State John Kerry, who led the talks with Russian Foreign Minister Sergey Lavrov and 18 other foreign ministers, called the resolution "a milestone," because it sets time frame and specific plans.

"This council is sending a clear message to all concerned that the time is now to stop the killing in Syria and lay the groundwork for a government that the long-suffering people of that battered land can support. After four and a half years of war, this is the first time we have been able to come together at the United Nations in the Security Council to embrace a road forward," Kerry said.

"During that time, one Syrian in 20 has been killed or wounded; one in five is a refugee; one in two has been displaced. The average life expectancy in Syria has dropped by 20 years,' Kerry continued. "We need to reverse the course, and that is the council's goal here this afternoon: to put an end to the indiscriminate bombing, the acts of terror, the torture, and the bloodshed. And our shared task is to find a way to make that happen"

The draft resolution requests that U.N. Secretary-General Ban Ki-moon convene representatives of the Syrian government and opposition "to engage in formal negotiations on a political transition process on an urgent basis, with a target of early January 2016 for the initiation of talks."

Within six months, the process should establish "credible, inclusive and non-sectarian governance," with U.N.-supervised "free and fair elections" to be held within 18 months.

The draft calls the transition Syrian-led and Syrian-owned, stressing that the "Syrian people will decide the future of Syria."

However, the agreement does not guarantee or even mention if Assad will leave power, CBS News State Department correspondent Margaret Brennan reported. That key sticking point is being avoided to allow both President Obama and Assad's patron, Russian President Vladimir Putin, to save face.

The draft also says cease-fire efforts should move forward in parallel with the talks, and it asks Ban to report within a month of the resolution's adoption on a way to monitor the cease-fire.

The draft notes that the cease-fire "will not apply to offensive or defensive actions" against groups considered terrorist organizations, meaning that airstrikes by Russia, France and the U.S.-led coalition apparently would not be affected.

Meanwhile Friday, some 20 foreign ministers tackled those and other difficult issues for a possible end to Syria's civil war, including sorting out which Syrian groups will represent the opposition in peace talks in the new year.

Jordanian Foreign Minister Nasser Judeh said he presented lists submitted from each country of groups they consider terrorist organizations. He said some countries "sent 10, 15, 20 names" and others more.

"Now I think there will be follow-up steps in terms of countries meeting again to set criteria which will help filter the list," said Judeh, whose country is tasked with putting the final list together.

Others around the table included the United States, key European nations, Saudi Arabia and top Syria allies Russia and Iran.

Chinese Foreign Minister Wang Yi said the two most important issues are launching political negotiations among Syrian parties and implementing a U.N.-monitored cease-fire. "Without peace talks, the cease-fire cannot be sustained. Without a cease-fire, peace talks cannot continue to produce results," he said.

Wang noted the "severe threat posed by international terrorism," a reference to ISIS, which has exploited the chaos to seize large parts of Syria.

A peace plan agreed to last month by 20 nations meeting in Vienna sets a Jan. 1 deadline for the start of negotiations between Assad's government and opposition groups.

That deadline is "too ambitious a timetable," the U.N. representative for the Syrian National Coalition, the main Western-backed opposition group, told reporters Friday. Najib Ghadbian estimated that a month of preparation is needed.

Ghadbian also said a comprehensive solution to the conflict requires "the removal of all foreign troops from Syria, all of them," including Russia, which began airstrikes there in September. The strikes are focused on more moderate forces fighting Assad in areas where ISIS has little or no presence.

The coordinator of the opposition team that will negotiate with the Syrian government, former Prime Minister Riad Hijab, said in Saudi Arabia on Friday that Assad should have no role during a transitional period. He also called for "confidence-building measures" such as the lifting of a siege imposed on rebel-held areas and a halt to airstrikes.