One may distinguish between two notations to present the chronotopologic points, see Fig. 2.4.

In the first notation (Fig. 2.4A) the spatial and temporal coordinates are separately displayed as in Eq. (2.1a), i.e., in the R2,1 domain one can write that,

In the second notation (Fig. 2.4B), the spatial and temporal coordinates are jointly displayed as in Eq. (2.1b), i.e., in the R2+1 domain one can write that,

As noted earlier, although the formal differences between Eqs. (2.4a) and (2.4b) are merely notational (space and time coordinates are distinguished by a semicolon in Eq. (2.4a) vs. a comma in Eq. (2.4b)), the differences in physical meaning are significant (the semicolon signifies that space and time are separate entities, whereas the comma means that they form a unique whole).

The notion of the chronotopologic lag between two points, Eqs. (2.2a) and (2.2b), emerges naturally, since the study of a phenomenon in its domain of occurrence requires the simultaneous consideration of pairs of points. The Rn,1 description explicitly distinguishes time lag (separation) from space lag h, whereas the Rn+1 description does not explicitly distinguish time lag from space lag.^h

The metrical structure of Eqs. (2.3a) and (2.3b) is arguably the most fundamental chronotopologic feature of a phenomenon. So, |p|, or, equivalently, the distance |h| and the time separation , are among the most salient aspects of the chronotopologic description of a phenomenon affecting the CTDA results.