Sri Lankan authorities say they have opened up the huge refugee camps in the north of the country.
This will allow, for the first time, increased freedom of movement to the displaced Tamils who have been forcibly kept there since earlier this year.
The government says the camp-dwellers will now be free to leave after giving their details to the authorities.
But with northern Sri Lanka devastated and mined, some of the displaced will want to stay on in the camps for now.
The gates of the biggest camp, Menik Farm, have been opened, Maj Gen Kamal Gunaratne, the officer-in-charge, told the BBC by telephone.
He said he expected a huge rush of people wanting to leave, but things were going very smoothly and the mood was good.
Before going out, families and individuals were filling in two copies of a form, leaving one with the authorities so movements could be monitored, he said.
Gen Gunaratne said people leaving on Tuesday do have to return and that anyone trying to leave permanently would be "tracked down".
Sudden exodus?
Many people doing aid work in these camps have felt ambivalent about giving assistance.
Some see them as "open prisons" because the people living there have had no free choice about staying inside.
The government says that is all changing. It says there will not be limits on how long they can stay away.
But top officials have told the BBC that those still registered as living there do not have anywhere else to go and live and will not be allowed to "go missing".
People living in the nearest town, Vavuniya, say they do not expect any sudden outflow.
Others who have been miserable there will want to escape completely, but with a heavy security presence in the region that will not be easy.
The government, which faces elections in January, has in the past month stepped up the formal process of returning people to the villages; the numbers living in the camps have halved.
The authorities have been screening them all for possible links to the Tamil Tigers.
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