sentences:  Unlike properties above, where replacement of to changed numbers but not geometry, the sign reversal of the quadratic form results in a distinct Clifford algebra, so for example and are not isomorphic.Just like over any vector space, there are pseudo-Euclidean tensors.Like with a Euclidean structure, there are raising and lowering indices operators but, unlike the case with Euclidean tensors, there is no bases where these operations do not change values of components.