---
oid: "0"
asn1-notation: "{itu-t(0)}"
description: "International Telecommunication Union - Telecommunication standardization sector (ITU-T)"
last-modified: "2024-04-26"
tags: [oid-repository]
---

## OID: `0`

```asn1
{itu-t(0)}
```

### Description

International Telecommunication Union - Telecommunication standardization sector (ITU-T)

### Supplementary information

Subsequent OIDs identify ITU-T Recommendations (not jointly published with ISO/IEC) and ITU members.
This arc is also called `ccitt(0)` to recall that CCITT used to be an organization independent from ITU-T.
Identifier **`itu-r`** was added by ITU-T Study Group 17 in March 2004 (and was ratified by ISO/IEC JTC 1/SC 6 in Sep 2005). It can only be used as a 'NameAndNumberForm' (that is, followed by number `5` between parentheses) for OIDs that commence with `{itu-r(0) `[`r-recommendation(5)`](https://oid-base.com/get-md/0.5)`}` (see [Rec. ITU-T X.680 \| ISO/IEC 9834-1](https://itu.int/rec/T-REC-X.680/en), clause A.5, for more details on this specific case). Consequently Unicode label "`ITU-R`" can only be used for "[OID-IRIs](https://oid-base.com/faq.htm#iri)" that designate OIDs under the `{itu-r(0) `[`r-recommendation(5)`](https://oid-base.com/get-md/0.5)`}` arc.
Operation is in accordance with [Rec. ITU-T X.660 \| ISO/IEC 9834-1](https://itu.int/rec/T-REC-X.660/en) and is under the guidance of [ITU-T Study Group 17](https://itu.int/ITU-T/studygroups/com17/index.asp).
All decisions related to subsequent arcs, other than the assignment of additional secondary identifiers to top-level arc `0` (see Rec. ITU-T X.660 \| ISO/IEC 9834-1, clause A.5), will be recorded as amendments to Rec. ITU-T X.660 \| ISO/IEC 9834-1 (such changes to the joint ITU-T \| ISO/IEC text will be regarded as editorial by ISO).
From Rec. ITU-T X.660 \| ISO/IEC 9834-1, "the top-level arcs are restricted to three arcs numbered `0` to `2`; and the arcs beneath root arcs `0` and `1` are restricted to forty arcs numbered `0` to `39`. This enables optimized encodings to be used in which the values of the top two arcs for all arcs under top-level arcs `0` and `1` encode in a single octet in an object identifier encoding (see the Rec. ITU-T X.690 series \| ISO/IEC 8825 multi-part Standard).

### Registrant

Name: ITU-T Study Group 17

### Child OIDs

- [OID `0.0`](https://oid-base.com/get-md/0.0): `recommendation(0)`
- [OID `0.1`](https://oid-base.com/get-md/0.1): `question(1)`
- [OID `0.2`](https://oid-base.com/get-md/0.2): `administration(2)`
- [OID `0.3`](https://oid-base.com/get-md/0.3): `network-operator(3)`
- [OID `0.4`](https://oid-base.com/get-md/0.4): `identified-organization(4)`
- [OID `0.5`](https://oid-base.com/get-md/0.5): `r-recommendation(5)`
- [OID `0.9`](https://oid-base.com/get-md/0.9): `data(9)`

This is a [frozen OID](https://oid-base.com/faq.htm#leaf) (no more child OIDs can be added to the existing ones).

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[Terms of use](https://oid-base.com/disclaimer.htm.md)