Explicitly, let T be a tensor field of type (p,q).
This identity hold for tensor fields of all orders.
It is therefore a tensor field of rank three.
Note that the tensor field only needs to be defined on the curve for this definition to make sense.
A tensor field is an element of this set.
The same is true in general relativity, of tensor fields describing a physical property.
It is also possible for a tensor field to have a "density".
The solution is a metric tensor field, rather than a wavefunction.
The theory seems to contain an asymmetric tensor field and a source current vector.
The result can be generalized to higher rank symmetric tensor fields.