CHAT Format Overview

Status: Reference Last updated: 2026-10-20 (commit f7e32e22)

CHAT (Codes for the Human Analysis of Transcripts) is a transcription format used by CHILDES and TalkBank. These chapters introduce its representation in Chatter; the CHAT manual remains the format reference. Parser recovery is an implementation feature, not permission to treat malformed input as valid.

File Anatomy

A typical transcript has a metadata preamble, speaker turns and optional dependent annotations:

@UTF8
@Begin
@Languages:	eng
@Participants:	CHI Target_Child, MOT Mother
@ID:	eng|corpus|CHI|2;6.||||Target_Child|||
@ID:	eng|corpus|MOT|||||Mother|||
*MOT:	what do you want ?
%mor:	ADV|what AUX|do PRON|you VERB|want ?
%gra:	1|4|OBJ 2|4|AUX 3|4|NSUBJ 4|0|ROOT 5|4|PUNCT
*CHI:	I want cookie .
%mor:	PRON|I VERB|want NOUN|cookie .
%gra:	1|2|NSUBJ 2|0|ROOT 3|2|OBJ 4|2|PUNCT
@End

A CHAT file consists of:

1. @UTF8: required first line, declares UTF-8 encoding
2. @Begin: marks the start of the transcript
3. Headers: lines starting with @ that provide metadata (participants, languages, IDs, etc.)
4. Utterances: blocks consisting of:
   • A main tier (line starting with *SPEAKER:) containing the transcribed speech
   • Zero or more dependent tiers (lines starting with %tier:) containing annotations
5. @End: marks the end of the transcript

Key Conventions

• Tab separation: a tab character separates the tier prefix from its content (e.g., *CHI:⟶content)
• Terminators: ordinary utterances end with a terminator (., ?, !, or special forms like +...). The legacy CA option has a specific missing-terminator exception; CA symbols alone do not enable it.
• Line continuation: long lines wrap with a tab at the start of continuation lines
• Speaker codes: short identifiers; the validator accepts up to seven characters from A-Z, 0-9, _, -, '; three uppercase letters is the convention (e.g., CHI, MOT, FAT, INV)
• Media linking: timestamps link transcripts to audio/video via bullet markers

What validation establishes

Chatter checks syntax and supported semantic rules. A successful parse may still produce diagnostics, and a recovered model is not evidence that the original input is valid. Validation does not establish transcription accuracy, recording identity or acoustic timing accuracy.

Start with Headers, Utterances and Dependent Tiers. For a runnable create/validate/repair exercise, use the Quick Start.

References

• CHAT Manual: the canonical reference
• TalkBank: the data repository

This page last changed: 2026-10-20 (commit f7e32e22). The whole book last changed: 2026-10-27 (commit 5bfee2f9).