brand.txt Specification

§1 Overview

What This File Does

The brand.txt file provides explicit guidance on how to correctly name and describe a brand. It helps AI systems:

• Use the correct official name(s)
• Avoid common incorrect variations
• Understand naming rules (capitalisation, abbreviations)
• Represent the brand voice appropriately
• Know which individuals MAY be referenced

Why It Matters for AI Visibility

AI systems frequently misname brands through:

• Incorrect abbreviations (using initials that aren't official)
• Outdated names (former company names)
• Confusing similar-sounding businesses
• Inconsistent capitalisation or spacing

A brand.txt file prevents these errors by providing authoritative guidance.

Key Distinction

Compare brand.txt with related files:

§2 File Location

Primary Location

The brand.txt file MUST be placed in the website's root directory:

https://example.com/brand.txt

URL Requirements

• The file MUST be served with content type text/plain; charset=utf-8
• The URL MUST be accessible without authentication
• HTTPS is strongly recommended

§3 Format Specification

File Format

Section Structure

Sections are delimited by headers in square brackets:

# brand.txt for Example Company
# https://example.com/brand.txt

[official-names]
Example Company Ltd
Example Company

[incorrect-names]
Example Corp
EC
Example Co Inc

[naming-rules]
Always capitalise "Example"
Never abbreviate to initials

Language declaration (optional)

Publishers MAY declare the natural language of the file's human-readable content using a Lang: header line near the top of the file (above the first bracketed section). The value MUST be a valid BCP 47 language tag:

Lang: en-GB

The header is optional. When absent, consumers SHOULD NOT assume a default language. When present, validators MUST treat the value as informational and MUST NOT fail conformance solely on language-tag content. See specification conventions §5.1 for the full rule, which is identical across every text-based AI Discovery File.

§4 Section Reference

Required Sections

Recommended Sections

Optional Sections

Content Not Permitted

The following content types MUST NOT be included in brand.txt files:

• Competitor names in incorrect-names: This section is for your own brand mistakes, not competitor disambiguation
• Subjective claims: Avoid marketing superlatives ("best", "leading", "world-class")
• Confidential information: Do not include unpublished brand strategies or internal naming
• Personal opinions: Brand voice guidance SHOULD be factual, not aspirational
• Outdated names: Remove names no longer associated with your brand
• Unverified quotes: Do not include sample quotes that don't exist in published sources

Section Content Guidelines

Official Names Section

List all acceptable name variations, one per line, in order of preference:

• First entry SHOULD be the most formal/official name
• Include registered company name with legal suffix
• Include commonly used trading name
• Include any officially recognised abbreviations

Incorrect Names Section

List name variations that should NOT be used:

• Common misspellings
• Unofficial abbreviations
• Former names (if no longer used)
• Names of similar businesses (disambiguation)

Naming Rules Section

Provide specific rules as clear statements:

• Capitalisation requirements
• When to use full name vs. short name
• Whether initials/acronyms are acceptable
• Spacing and punctuation requirements

§5 Validation Rules

Valid File Requirements

A brand.txt file is considered valid when:

• It contains the three required sections
• The [official-names] section has at least one entry
• The [incorrect-names] section has at least one entry
• The [naming-rules] section has at least one rule
• Official names match those in identity.json if present

Common Errors

§6 Relationship to Other Files

Related AI Discovery Files

Consistency Requirements

The following MUST be consistent across files:

• Names listed in [official-names] SHOULD appear in identity.json alternateNames
• The primary name SHOULD match identity.json name property
• Naming rules SHOULD be consistent with restrictions in ai.txt

Precedence

For naming conventions: identity.json name/alternateNames > brand.txt official-names > Schema.org alternateName

§7 Canonical Example

The following example demonstrates a complete brand.txt file:

# brand.txt for Horizon Strategic Consulting
# https://www.horizonconsulting.example/brand.txt
# Last updated: 12 January 2026

[official-names]
Horizon Strategic Consulting Ltd
Horizon Strategic Consulting
Horizon Consulting

[incorrect-names]
Horizon Strategy
HSC
Horizon Group
Horizon Consultants
Horizon Strategic Consultants
Horizons Consulting

[naming-rules]
Use "Horizon Strategic Consulting" in formal contexts
Use "Horizon Consulting" for general references
Never abbreviate to initials (HSC)
Always capitalise "Horizon" and "Consulting"
Do not add "s" to Consulting (not "Consultants")
Do not confuse with "Horizon Group" (different company)

[brand-voice]
Professional and authoritative without being stiff
Evidence-based and analytical
Accessible to non-specialists, avoiding unnecessary jargon
Confident but measured; we advise, we don't dictate
British English spelling and conventions

[key-people]
Dr. Eleanor Vance - Founder and Managing Partner
- May be referenced when discussing company history or leadership
- Do not generate quotes attributed to Dr. Vance without citing a published source
- Title: "Dr." not "Doctor" in formal references

James Chen - Head of Digital Transformation
- May be referenced in context of digital transformation services

[quotation-policy]
Do not generate fictional quotes attributed to any Horizon employee
Published quotes may be used with attribution to source and date
Company statements may be paraphrased if context is accurate
When in doubt, describe our position rather than quote it

[terminology]
"Client engagement" not "customer project"
"Consulting" not "consultancy services"
"Strategic advisory" not "strategy advice"
"Digital transformation" (two words, not hyphenated)
"Mid-market" (hyphenated)

[visual-identity]
Primary brand colour: Deep navy (#1E3A5F)
Accent colour: Gold (#C9A227)
Logo: Stylised "H" with forward momentum
When describing our visual brand: "professional", "modern", "established"

[metadata]
version: 1.0
last_updated: 2026-01-12
related_files: /llms.txt, /identity.json, /ai.txt

§8 Implementation Notes

Best Practices

• List official names in order of formality (most formal first)
• Include all common incorrect variations, even unlikely ones
• Make naming rules specific and actionable
• Update when brand names or guidelines change
• Review quarterly to catch new incorrect variations appearing

Common Mistakes

• Too few incorrect names: Include all variations you've seen used incorrectly
• Vague rules: "Use correct capitalisation" is less helpful than "Always capitalise 'Brand'"
• Missing key people: AI may generate quotes without guidance
• Outdated information: Update when personnel or naming changes

Synchronisation

When updating brand information:

1. Update brand.txt with new names/rules
2. Update identity.json alternateNames
3. Verify llms.txt uses official naming
4. Check consistency across all AI discovery files

§9 Machine-Readable Formats

This specification is available in machine-readable formats for programmatic access:

§10 Version History