Without going too deep into the complex nature of time, we can safely say that time flies - tempus fugit!

Therefore, inspired by informal representations of duration like this EveXL uses the [<- INTERVAL-ID ->] notation to apply conditions on interval durations. For instance, the following expression should be read as

We can compare interval durations. For example, the following expression means that:

This will match an interval of red readings shorter than another interval of blue readings.