# Patterns, seats and ad-hoc shifts

A shift pattern describes cover that repeats at a site — a start and end time, the days it runs, and how many people it needs. Each person the pattern needs is a seat. A shift that does not belong to any pattern is ad-hoc.

"Seat" is a word for the idea, not a word on screen. What the screen shows is described below.

![The roster on Week + Patterns. Two pattern rows — Gatehouse Day, badged 2 staff, and Gatehouse Night, badged 1 staff — then an Ad-hoc row. Gatehouse Day gives each day two stacked places: most hold a named officer, Wednesday's second place reads Open shift, Thursday's is awaiting an agency, and Saturday's is an empty Slot 2.](/docs/img/roster-week-patterns.png)

## Which roster view is this about?

The roster opened on **Week** with the row toggle set to **Patterns** — how an organisation opens it by default, and the only view with a row per pattern.

**Employees** lists shifts under the person working them instead. A shift nobody is assigned to has no row to sit in, so open seats and unfilled ad-hoc shifts do not appear there.

**Month** lays the site out as a calendar. It still shows each pattern's open places day by day, but it has no pattern rows, and a shift belonging to no pattern does not appear on it at all.

Agencies open the roster on **Week** + **Employees**. Patterns are set up on an organisation's sites, so an agency that switches to **Patterns** may find no rows to show.

## What is a seat?

A pattern that needs two guards on a Monday night has two seats on that Monday. Its row on the roster carries a badge reading **2 staff**, and it gets a cell on each day of the week it runs. That cell shows one place per seat; where a pattern needs more than one person, the empty places are numbered **Slot 1**, **Slot 2** and so on.

A place with no shift in it is an open seat. The cell's menu offers **Add Shift** to fill it in-house, and when you raise a request, **Pick existing slot** offers the same open places for an agency to cover.

A pattern can also be limited to a range of dates. Its row is drawn for any week that range touches, so a day outside the range can still show empty places on the roster that **Pick existing slot** will not offer.

## Why does the slot picker offer fewer seats than the pattern needs?

**Pick existing slot** stops offering a seat once a shift occupies it — a shift with somebody assigned, a shift already sent to an agency, and a shift added to the roster but not yet filled all count. The cell still needs the same number of people; what changed is how many of those places are free.

A shift sitting in the cell with nobody assigned and no request against it is still offered. What changes is its form: it comes up as that shift rather than as an empty seat.

Cancelling a shift is the exception, and the two surfaces disagree about it. On the roster a cancelled shift is not one of the cell's places: unless **Hide cancelled** is ticked it is drawn as an extra tile beneath them, so a cell that has had a shift cancelled can show more tiles than the pattern has seats. After a cancellation, read the cell itself rather than trusting either count.

## What makes a shift ad-hoc?

An ad-hoc shift has no pattern behind it. It is created for a one-off need — extra cover, a request raised through **New ad-hoc slot** for a hand-picked date and time rather than from a pattern seat, or a shift added outside the normal rota. Because it belongs to no pattern cell, **Week** + **Patterns** collects all of a day's ad-hoc shifts into one row beneath the pattern rows, labelled **Ad-hoc** with **Unscheduled — no pattern** under it.

![The same week's grid, with the Ad-hoc row at the bottom holding a single 14:00–22:00 shift on the Saturday. The pattern rows above it run 07:00–19:00 and 19:00–07:00, so the ad-hoc shift sits in no cell of either.](/docs/img/roster-adhoc-row.png)

A site can hold more than one ad-hoc shift starting at the same time. When you raise a request through **New ad-hoc slot** and the site already has an ad-hoc shift starting then, the form asks you to confirm before adding a second — that confirmation is what separates a deliberate second shift from an accidental double submission.

Your request attaches to the shift already there, rather than adding a second, only when that shift meets every one of these conditions:

- it runs the same hours, to the minute;
- it is not cancelled;
- no employee is named on it;
- no other request is already against it;
- nobody is assigned to work it.

If any one of them fails, you are asked to confirm instead.

A pattern seat starting at the same time never raises the question. How many shifts its cell can hold is governed by the pattern's own seat count.

## Related

- [How a request becomes a rostered shift](/docs/concepts/how-a-request-becomes-a-rostered-shift)