TNF (Type Name Format)
A 3-bit field in the NDEF record header that indicates how to interpret the record type. Values range from 0x00 (empty) to 0x07 (reserved), with 0x01 (NFC Forum well-known) and 0x02 (MIME type) being most common.
What Is TNF?
TNF (Type Name Format) is a 3-bit field in every NDEF record header that tells the receiving device how to interpret the record's Type field. Without TNF, a reader could not distinguish between a URI, vCard, and custom binary data.
TNF Values
| Value | Name | Description | Example |
|---|---|---|---|
| 0x00 | Empty | No type, ID, or payload | Placeholder |
| 0x01 | Well-Known | NFC ForumNFC ForumFundamentalsIndustry body developing NFC standards, specifications, and certifications since 2004Click to view → RTD naming | "U" (URI), "T" (Text) |
| 0x02 | MIME Type | RFC 2046 media type | "text/vcard" |
| 0x03 | Absolute URI | RFC 3986 URI | "https://schema.org" |
| 0x04 | External Type | Reverse domain naming | "android.com:pkg" |
| 0x05 | Unknown | Opaque binary payload | Raw data |
| 0x06 | Unchanged | Continuation chunk | Chunked records |
| 0x07 | Reserved | Future use | Not used |
How TNF Drives Record Dispatch
TNF 0x01 (Well-Known): The OS looks up the NFC Forum Record Type Definition. "U" decodes as a URI record; "T" as a text record.
TNF 0x02 (MIME): The type string is treated as a MIME type. text/vcard triggers the contacts app; application/vnd.wfa.wsc triggers Wi-Fi settings.
TNF 0x04 (External): The OS looks for an app registered for that external type. android.com:pkg is the AAR forcing app launch on Android.
TNF 0x05 (Unknown): Raw binary data. Only explicitly registered applications can process these.
Memory Efficiency
TNF occupies zero extra bytes — it shares the header byte with MB, ME, CF, SR, and IL flags. Well-Known types (TNF 0x01) are especially compact:
| Well-Known Type | Type Bytes | vs MIME Equivalent |
|---|---|---|
| "U" (URI) | 1 byte | "application/uri": 16 bytes |
| "T" (Text) | 1 byte | "text/plain": 10 bytes |
Practical Guidelines
- Use TNF 0x01 for standard NFC interactions (URLs, text, smart posters) — widest support, most compact.
- Use TNF 0x02 when data has a natural MIME type (vCards, Wi-Fi, JSON).
- Use TNF 0x04 for app-specific data that should launch your custom app.
- Avoid TNF 0x03 (Absolute URI) — rarely used and less efficient than TNF 0x01 + "U".
Related Terms
Related Guides
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The NFC glossary is a comprehensive reference of technical terms, acronyms, and concepts used in Near Field Communication technology. It is designed for developers, product managers, and engineers who work with NFC and need clear definitions of terms like NDEF, APDU, anti-collision, and ISO 14443.
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