The authoritative version of this thing.
There is no requirement that the thing which is pointed to by this property be accessible or dereferencable, only that statements about that thing be considered the “canonical” statements regarding the underlying concept that this thing represents. Note, however, that this thing and the “canonical” thing are kept formally distinct; they may have different properties.
This property ultimately serves two purposes :—
It helps to establish identity of underlying concepts, in that two things with the same canonical can be assumed to be different noncanonical versions of the same canonical thing.
When a means of dereferencing the canonical thing is available, it allows processors to use it in place of this thing in situations where that would be desirable.