Haflagah
Haflagah is based on the interval from the beginning of one Re'iyah to the beginning of the next Once an interval exists, the next relevant date can be anticipated using the same distance according to the applicable rules
Haflagah counts two consecutive source dates inclusively: the day difference plus 1 Count that interval from the latest source, including its day, in its Onah Fewer than two source events produce no interval Process reports are not measurement anchors
A new interval retains its own length and every earlier longer length Thus 40,27,22,25 retain 40,27,25 Full source history remains available even while the switch is off
In this profile, Or Zarua adds the preceding Onah only to monthly and interval concerns: before day D, night D; before night D, day D−1