I think 'scope ref' is better.
'in' = 'const scope', then 'in ref' = 'const scope ref'.
bool opEquals(in ref T rhs) const { ... }
Kenji Hara
As far as I studied the code, something like @ref isn't possible, because ref is already a keyword. Except as Pseudo-property. But this is a combination of '@' and 'ref' so that both, '@ref' and '@ ref' would be valid.
I still like the idea of '&A'.