# Writing a rule


> The three sections of a rule: dates, time of day, and days of week. What each accepts and what leaving one alone means.
On a playlist's **Schedule** tab, choose **Add a rule**. A rule has three sections.

## Dates

**Any date**, or a start and an end.

You can also add **except** dates: individual days the rule skips. Holidays, a shutdown week, a day the building is closed.

Leaving this as Any date means the rule has no start and no end.

## Time of day

**All day**, or **specific hours** with a start and an end.

A time window is inclusive at both ends, and it cannot end before it starts. The editor refuses to save one that does.

## Days of week

Individual days, or the presets **Every day**, **Weekdays**, and **Weekend**.

A rule has to include at least one day. Deselecting them all is refused rather than silently producing a rule that never matches.

## Leaving a section alone

Anything you do not restrict stays unrestricted, which is the thing most likely to surprise you.

A rule that only sets 09:00 to 17:00 means those hours **on every day, forever**. If you meant weekdays, say weekdays. The rule does not infer it.

## The summary under the rule

As you edit, the dialog shows what the rule means in plain language. Read it before saving. It catches the case where every field is individually right and the combination is not.

## Saving

Rules are not live until you save the playlist. Once saved, they reach every assigned screen on its next check-in.