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
"TimeFlow" is an interval of time (line 1)
Duration of TimeFlow interval is greater than or equal to 3 units of time (line 3)
We can compare interval durations. For example, the following expression means that:
"short" is an interval of time during which the "color" sensor reads the value "red" (line 1)
"long" is an interval of time during which the "color" sensor reads the value "blue" (line 2)
the "short" interval is shorter than "long" (line 4)
This will match an interval of red readings shorter than another interval of blue readings.