ABSTRACT
The meaning of the notation is explained in the text at its first use. Two level indexes (two level subscripts and two level superscripts) are used
in order to denote precisely values of variables with respect to time axes and relative to spatial coordinate systems (frames). The norm of a vector together with the vector direction do not represent,
in general, completely the vector concerned because its sense can be opposite to the sense of the colinear unity vector that determines the positive sense. We will use the algebraic value of a vector, which is measured along the vector direction and with respect to the sense of the unity vector. It and the unity vector determine completely the corresponding colinear vector. However, if a vector is not colinear with the accepted and fixed constant unity vector then it is completely determined by both its matrix value and the unity vector.
