The current transformation matrix is, in fact, a set of matrices that are maintained to relate the sense of position, orientation and size between objects and the world coordinate system. While the internal form of these (and their interdependencies) are not available to the user, it is convenient to be able to store, assign and use them. The transformation data type defines variables to do that.
There are no components of a transformation available to the user. A transformation may not be used as a literal.