Information-wise it's nothing more and slightly less. So I'd suggest checking the other source.
Wait, I thought it was for a value that could appear on the "left" hand side of an expression…
It is perhaps better considered as representing an object ‘‘locator value’’.
If you need proof you can look it up in the standard:
Not necessarily. It might also inhabit a register.
> When C++ introduced the const keyword...
As of Stroustrup's first publication of “The C++ Programming Language”, C++ has always had the `const` qualifier.
There may be more errors, but this should be enough to discard this writeup and seek enlightenment from a qualified source.