The arcane formals(function(x){})$x

What is the object formals(function(x){})$x?

It's found in the formals of a function, bound to arguments without default value.

Is there any other way to refer to this strange object? Does it have some role other than representing an empty function argument?

Here are some of its properties that can be checked in the console:

> is(formals(function(x){})$x)
[1] "name"      "language"  "refObject"
> formals(function(x){})$x

> as.character(formals(function(x){})$x)
[1] ""

EDIT: Here are some other ways to get this object:

alist(,)[[1]]
bquote()
quote(expr=)