Shift

A shift is not just a start time. It carries the tolerance before a late mark, the breaks that are paid or unpaid, and the weekly off pattern that goes with it. Two people clocking in at the same moment can be on time and late respectively, because they are on different shifts.

Shifts become genuinely hard in three situations. A night shift crossing midnight belongs to the day it began, so a punch at 2am attaches to the previous evening's shift — grade it against the calendar day instead and every night worker's week splits into half-days. A rotating pattern moves people between shifts on a cycle, so the correct shift for a given day is a lookup rather than a constant. And an alternate pattern, like alternate Saturdays or four-on-four-off, repeats over more than a week, which a plain weekly grid cannot express.

The reason it matters beyond scheduling is that attendance, overtime, late marks and payable hours are all computed relative to the assigned shift. A roster that is approximately right produces payroll that is approximately right, which is another way of saying wrong.