FWIW, you can see some info here:
http://forum.dlang.org/thread/k7afq6$2832$1@digitalmars.com

Yeah, I read that when it happened. But I don't want to read entire threads months afterwards to see how a feature work.

And, honestly: *no-one* coming from outside this discussion group can understand that 2.061 brings UDA, or what UDA are.

Funny thing, the syntax in the original post by Walter was deprecated from the beginning. The correct syntax is:

@(4) int a;

Or

struct Foo
{
int b;
}

@Foo(3) int c;

I'll start a new thread on this. This seems to be a major new feature and it appears nowhere!