teirmijyfau lujvo

The elapsed time/duration between x1 (nu, or time-/date-stamp) and x2 (nu, or time-/date-stamp) is equal to the elapsed time/duration between x1 and x3 (nu, or time-/date-stamp), such that x2 occurred no later than x3 (thus, x1 is also a temporal midpoint between them), in frame of reference x4.

In practical usage, there is usually some sort of importance placed upon or recognition given to each of the three events, some sort of thematic interrelation between at least one pair of them is implied, and often one of them (usually x3 because that can be calculated in advance) will either be the current time (at utterance) or a moment of recognition/reflection; in practice, x2 is often the birth or start of something (an event or entity/object) and x1 is its death or end (but beware sumti-raising when discussing said object!); for example, if x2 is the construction of the Berlin Wall and x1 is its destruction, then x3 is a particular date in the late-201Xs (such as 13 Apr. 2019) dependent on definitions of "construction" and "destruction". See also: "teimjau".

In notes:

x1 (nu, or time-/date-stamp) is the event/moment in time when the elapsed time/duration from the death or end of x2 (entity/object, or process) is equal to the temporal measure of its lifetime (elapsed time from its birth/beginning until its death/end), in frame of reference x3.