Looking at the code, it appears it should be in milliseconds: https://github.com/couchbase/couchbase-net-client/blob/master/Src/Couchbase/Utils/TimeSpanExtensions.cs#L35
The other overload for ToTtl that takes a TimeStamp, will return seconds, but the input is milliseconds.
Closing because CBSE that triggered it is closed.
Jeff Morris shouldn't we still make the change to ensure the code documentation is accurate? It isn't as urgent without the CBSE but I think it's still worth doing.
Michael Goldsmith sure, the CBSE was closed so I assumed it was no longer an issue. Feel free to re-open!
After further investigation, the Document.Expiry is described correctly, but I've added a commit to improve the TimeSpanExtensions.ToTtl(uint) method.