BANGKOK: Backed by China - and excluding the United States - the sprawling Regional Comprehensive Economic Partnership (RCEP) was poised to link half the world's people.
But it took a hit at the close of a three-day Association of Southeast Asian Nations (ASEAN) summit in Bangkok on Monday after India said it would not join the deal.
WHAT IS RCEP?
Launched in 2012, RCEP is a trade pact between the 10-member ASEAN bloc, along with China, Japan, South Korea, Australia, New Zealand and until recently, India.
It was supposed to link around 3.4 billion people and cover about 40 per cent of global commerce.
Without India's vast population, the deal will now include 2.1 billion people.
Its aim is to break down trade barriers and promote investment to help emerging economies catch up with the rest of the world.
WHAT WILL RCEP DO?
Exact details have yet to be released, but it will progressively lower tariffs across many areas.
Its backers say that just as importantly it will let companies export the same product anywhere within the bloc without having to meet separate requirements and fill out separate paperwork for each country.
"For a goods producer it's huge," said Deborah Elms of the Asian Trade Centre. "What we don't have now is a lot of Asian trade for final markets in Asia. This sets that up."
It gives an incentive for companies to build supply chains within the region even if they export outside.
The agreement also touches on services and on protecting intellectual property.
WHAT DOESN'T IT DO?
RCEP is not seen as such a "high quality" trade agreement as the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), among 11 Asia-Pacific countries, because it does not cover or harmonise as much.
Tariffs are agreed between countries rather than across the board. For some countries, sensitive issues such as agriculture will not be touched. It lacks provisions for liberalising state enterprises or protecting workers and the environment.
WHY DOES IT MATTER?
It mainly matters because it does not include the US - and is notably being backed by Beijing.
Observers say it will cement China's domination over its backyard as an economic partner with East and Southeast Asia, where it faces little competition from America since President Donald Trump pulled out of a trade pact of its own.
That deal, called the Trans-Pacific Partnership (TPP), was on track to be the world's biggest trade pact, until Washington pulled the rug out from under it, saying it funnelled off US jobs.
With Washington and Beijing embroiled in a trade spat of their own, RCEP's backers are hoping to finalise the deal next year even without India.
China is already the biggest source of imports and destination of exports for nearly all the RCEP countries. It will also be better placed to shape the region's trade rules.
Additional symbolism for China's rise at the expense of the United States came from the deal being agreed alongside an ASEAN summit to which Trump's administration sent a lower-ranking delegation than all other countries.
There, they were met by only three of the region's leaders instead of the full group of 10.
"China measures up commendably against the US diplomatic faux pas and India's RCEP withdrawal," said Siew Mun Tang of the Yusof Ishak Institute in Singapore.
WHAT ECONOMIC IMPACT WILL IT HAVE?
Even once signed, implementation would take months to start and years to complete. The complexity makes precise calculations hard, economists say.
The 15 participating countries make up nearly a third of the world's people (it would have been nearly half with India). RCEP members account for nearly a third of global domestic product, with India's departure making less of a difference.
WHAT WAS INDIA OPPOSED TO?
A few things.
It raised alarm about market access issues, fearing its domestic producers could be hard hit if the country was flooded with cheap Chinese goods.
Textiles, dairy and agriculture were flagged as three vulnerable industries.
Prime Minister Narendra Modi faced mounting pressures at home to take a tougher stance on the terms, and proved unbending as the RCEP negotiations came to a close.
Thailand was pushing to have the deal finished this year but a final agreement might not come until 2020 now.
READ: Negotiation outcome a major step forward for RCEP, India's position respected and understood: PM Lee
WHAT DOES INDIA'S ABSENCE MEAN?
India can join later and other countries - notably Indonesia and Japan - have been lobbying it hard to stay. But Modi was emphatic about rejecting terms the other members agreed.
"While India's exit devalues the pact, it also removes the single biggest obstacle to its completion," said Anthony Nelson of consultancy Albright Stonebridge.
India's biggest concern is a wave of cheap goods from China and elsewhere. For other countries, losing India means they won't access a market that is notoriously hard to get into, but also they won't be able to include India as easily in supply chains.
Supporters of the deal argue that India will lose investment while its consumers will pay more than they should.
Southeast Asian countries also see India as a counterweight to China's growing dominance.
"It's a missed opportunity for India," said Pavida Pananond of Thammasat University in Bangkok.
WHAT DOES IT MEAN FOR GLOBAL TRADE?
Just getting the deal done - even without India - is a boost for multilateral trade deals over the bilateral sort favoured by Trump.
Trump's tariff-raising trade war with China gave extra impetus to push ahead with RCEP, which had progressed only sluggishly since 2012.
WHAT ARE THE ODDS?
Despite the dramatic pullback from India, odds are still good for the ASEAN bloc to conclude the deal next year in Vietnam.
Diplomats also say India can still join if it changes course.
But it remains to be seen what impact the decision of a country with 1.3 billion people will have on the pact's prospects.
"I will leave it up to the political masters to decide," said Iman Pambagyo, a negotiator involved with the RCEP talks.