A "cessation of hostilities" has been in effect in Syria for three days, although both sides accuse the other of violations.
The accord was drawn up by Russia and the United States, and has the unanimous backing of the UN Security Council.
It applies to Damascus and most of its suburbs, the southern province of Daraa, and parts of Aleppo and Homs provinces.
What is not included is more than half of the country's territory that is controlled by Islamic State group (IS) militants or Al-Qaeda affiliate Al-Nusra Front.
- The unprecedented cessation of hostilities begins at 0000 local time (2200 GMT on Friday).
- Russia says it will suspend for one day its air strikes in Syria to support the agreement and avoid "bombing mistakes".
- The Syrian Observatory for Human Rights and militants report a precarious calm in the central regions around Homs and Hama, in Damascus and around Aleppo in the north. No air strikes are signalled against rebel regions.
- One exception is near Abbasid Square in Damascus, where about a dozen shells hit an area disputed for the past three years by government troops and rebels.
- A Geneva-based international working group issues a positive evaluation of the situation. Although a few incidents are noted, the UN estimates they have not torpedoed the ceasefire.
- Aircraft attack six locations in Aleppo province and one in Hama, the Syrian Observatory says. The director of a pro-rebel press agency says the aircraft were Russian.
- Russian Lieutenant General Sergei Kuralenko accuses rebels of violating the ceasefire nine times, but adds: "On the whole, the ceasefire regime in Syria is being implemented."
- The Saudi-backed High Negotiations Committee, which represents most of the opposition groups, says the ceasefire has been broken two dozen times by Syria's government and its allies, leaving 29 dead.
- Saudi Arabia directly accuses President Bashar al-Assad's regime and Russia of "ceasefire violations".
- The UN says it will distribute supplies to an extra 154,000 people in besieged areas over the next five days.
- The Observatory says that the death toll in areas outside jihadist control has fallen sharply since the ceasefire began, with 40 people killed on the first two days in areas where IS is not present, against 144 on Friday.
- Ten airstrikes hit part of the eastern town of Deir Ezzor controlled by IS group.
- Turkey shells IS group positions in northern Aleppo province in coordination with the US-led international anti-jihadist coalition.
- The UN human rights chief warns that thousands could die from starvation because of sieges that have affected more than 480,000 people. The Red Crescent begins delivering UN-provided hygiene supplies to the rebel-held town of Moadamiyet al-Sham southwest of Damascus.
- The international task force was to meet in Geneva to shore up the ceasefire, after UN chief Ban Ki-moon tells media that "by and large the cessation of hostilities is holding even though we have experienced some incidents".