Is it correct to speak of "magnitude of a spacetime interval"?
For instance, considering a pair of (distinct) events, $A$ and $B$, which are lightlike separated, is it correct to say that "the magnitude of the spacetime interval of event pair $A$ and $B$ is equal to 0"?
Further, considering two pairs of (distinct) events, both of which are spacelike separated, is it correct to say that "the ratio between the magnitudes of the spacetime intervals of these two pairs of events is a real number"?
Likewise, considering two pairs of (distinct) events, both of which are timelike separated, is it correct to say that "the ratio between the magnitudes of the spacetime intervals of these two pairs of events is a real number"?
Finally: Is "$s[ P, Q ]$" an appropriate notation to abbreviate "the magnitude of the spacetime interval of event pair $P$ and $Q$"?
