Slugline (Scene Heading)

A slugline (scene heading) is the capitalized line that opens every scene in a screenplay: INT. DINER — NIGHT. Three pieces of data — interior or exterior, location, time of day — and no more.

Writers underrate sluglines because they read as formatting. Production reads them as database records: script breakdown software ingests every slugline to build the schedule and budget. The set of unique locations, the count of night scenes, the INT/EXT ratio — the line producer's first pass at your movie's cost is substantially a query over your sluglines. EXT. — NIGHT is the expensive quadrant: lighting a night exterior costs multiples of a day interior.

Craft rules that mark a professional: be consistent (INT. SARAH'S APARTMENT and INT. SARAH'S PLACE read as two locations to the breakdown, and to a tired reader); keep them lean (— CONTINUOUS and — LATER only when time actually matters); and never bury action in a heading. Sloppy sluglines are a formatting tell that costs credibility before page five.

Our scorecard parses sluglines directly when scoring budget realism — your headings are literally data. For screenplay format as machine-readable text, see Fountain.