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# Default text box

A 64-bit rectangle that specifies an area to receive text (each 16 bits indicate top, left, bottom, and right, respectively) within the subtitle track.

## Overview

This rectangle must fill the track header dimensions exactly; that is, top is `0`, left is `0`, bottom is the height of the subtitle track header, and right is the width of the subtitle track header. See [Subtitle track header size and placement](/documentation/QuickTime-File-Format/Subtitle_track_header_size_and_placement).

---

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