Slugline rules and conventions

A slugline (also called a scene heading) is the all-caps line that tells the reader where and when a scene happens. It looks simple. It is, in fact, simple. But the rules around it — secondary headers, sub-sluglines, the mini-slug, time-of-day vocabulary — are where new writers most often look like new writers. This is the working reference.

What is a slugline?

A slugline is one all-caps line that opens a scene with three pieces of information: location prefix (INT./EXT./INT./EXT.), location, and time of day. It's the script's navigation — readers, line producers, first ADs all use sluglines to break the script into shootable chunks.

INT. KITCHEN — NIGHT

EXT. ROOFTOP — DAY

INT./EXT. CAR — MOVING — DAY

The location prefix

Three options:

• INT. — interior. The scene is inside.
• EXT. — exterior. Outside.
• INT./EXT. — both. The classic example is inside a moving car: the interior is the cabin, the exterior is the world streaming past. Used for any scene where camera will move between inside and outside without a hard cut.

Always followed by a period and a single space. Some old scripts use I/E.— don't. Modern readers expect INT./EXT.

The location

All caps. Specific enough to be unambiguous, short enough to fit on a line. The general-to-specific order is: building → room → sub-area, separated by either commas or em-dashes.

INT. JAKE'S APARTMENT — KITCHEN — NIGHT

INT. POLICE STATION, INTERROGATION ROOM 2 — DAY

EXT. BROOKLYN BRIDGE — DAWN

Both em-dashes and commas are accepted; pick one and be consistent. Final Draft and Arqo both default to em-dashes.

Time of day

Working vocabulary, in rough order of frequency:

• DAY — the default daytime.
• NIGHT — the default nighttime.
• DAWN / DUSK — the magic-hour windows. Use only if the lighting matters.
• MORNING / AFTERNOON / EVENING— when the time of day matters narratively but the lighting is just "daylight".
• CONTINUOUS — for a scene that picks up immediately after the previous one, in the same time frame. Used when crossing through a doorway or following a character into a new room.
• LATER — same location as the previous scene, some unspecified time later. Avoid in most cases — write a clean slugline instead.
• MOMENTS LATER — same as LATER, slightly warmer. Same advice.

FLASHBACK and PRESENT DAY are time-of-day-adjacent — used to mark non-linear time, not wall-clock. They go on the slugline: INT. KITCHEN — DAY (FLASHBACK) or EXT. PARK — DAY (1992). Some writers preferFLASHBACK: as a transition before the slugline; either is acceptable.

Secondary headers (sub-sluglines)

When you stay inside the same major location but move to a new area — kitchen to living room, lobby to elevator — you have two choices.

Option A: a full new slugline.

INT. JAKE'S APARTMENT — KITCHEN — DAY

Jake stands at the sink.

INT. JAKE'S APARTMENT — LIVING ROOM — DAY

He walks in carrying a glass.

Option B: a sub-slugline. Same indent as a slugline, all caps, but no INT./EXT. prefix. Used when the move is fast enough that the reader doesn't need a full reset.

INT. JAKE'S APARTMENT — KITCHEN — DAY

Jake stands at the sink.

LIVING ROOM

He walks in carrying a glass.

Sub-sluglines read faster but are slightly harder for line producers — they have to track them as part of the parent scene. As a rule: use a full slugline if the move involves meaningful re-blocking or a time gap; use a sub-slug if the camera essentially follows the character.

The mini-slug

A working writer's favourite tool. A one-line all-caps beat that names a sub-area or angle without committing to a full new scene. Used for pacing.

INT. KITCHEN — NIGHT

Jake reaches for a knife.

THE KNIFE

— rests on the cutting board, light catching
the edge.

JAKE'S HAND

closes around the handle.

Each mini-slug is a beat. The reader's eye stops, then starts. It's a way of writing rhythm onto the page without explicit camera direction. Cormac McCarthy's adapted scripts are full of them. So is The Social Network.

What slugline rules people argue about

Underlined or not?

Some scripts underline every slugline. Some don't. Final Draft's default is no underline. Underlined sluglines were once a network preference (and still are at some procedurals); modern feature readers don't expect them. Pick one and be consistent.

Bold sluglines?

Some 2010s-era TV writers bolded sluglines for readability. Showrunners are split. As a default: don't. If you bold, bold every slugline, never some.

Spelling out time of day?

DAY and NIGHT are the standard. Spelling out AFTERNOON or DAWN is fine. Writing 4:32 PM in a slugline is not — that's a stage direction, not a time of day.

Common slugline mistakes

• Slugline overload. INT. JAKE'S OLD APARTMENT IN BROOKLYN ON A RAINY NOVEMBER NIGHT — NIGHT is a sentence. Cut to the essential.
• Inconsistent location names. Pick a name for each location and use it forever.
• Missing slugline before a scene.Every scene needs one. If you're tempted to skip it because the action seems continuous, use a sub-slug or mini-slug instead.
• Time of day inside the location. INT. KITCHEN AT 3 A.M. — NIGHT. The 3 A.M. belongs in action: Jake stands at the sink. The microwave reads 3:02.

Most-asked questions

Do you put a period after INT?

Yes. INT. with a period. Same for EXT. The exception is the combined prefix INT./EXT. which has periods after both words.

What does CONTINUOUS mean in a slugline?

That the new scene starts the instant the previous one ended. Used when a character moves to a new location without a time gap — through a door, around a corner. Don't use it for two scenes happening minutes apart.

Do you capitalise the time of day?

Yes. Every part of a slugline is all-caps — location prefix, location, time of day.