# TEFCA identity and organization structure
The **Trusted Exchange Framework and Common Agreement** (**TEFCA**) uses **object identifiers** (**OIDs**) to designate unique organizations and records belonging to network participants. An OID is a globally unique identifier defined by the International Organization for Standardization (ISO).
## TEFCA OID types
We provide three OID types you must use within TEFCA:
| **OID type** | **Description** | **OID structure** |
| --- | --- | --- |
| Organization | Corresponds to your organization within TEFCA. | `2.16.840.1.113883.3.6147.450.1.X.XXXX.X.X.1` |
| Patient | Corresponds one-to-one with your Master Patient Indexes (MPIs). We create the first one for you. If you have multiple MPIs, we recommend you create a patient OID for each MPI in your system. | `2.16.840.1.113883.3.6147.450.1.X.XXXX.X.X.2` |
| Document | Corresponds one-to-one with each document you exchange. Each document must have its own unique OID, which can either be a Redox-generated OID followed by your ID (e.g., `…3.1^12345`) or a version 4 UUID. [Learn more about version 4 UUIDs](https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)). | `2.16.840.1.113883.3.6147.450.1.X.XXXX.X.X.3` |
> **Using an existing OID**
>
> Network Onramps pricing requires that you use the Redox-generated OID. If you would rather use an existing OID, talk to your Account Manager to discuss needs and get pricing information.
To break down the OID structure:
| **OID segment** | **Notes** |
| --- | --- |
| `2.16.840.1.113883.3.6147.450` | This is Redox. |
| `X` | The first `X` represents the Redox deployment: `0`: local development `1`: non-production `2`: production |
| `XXXX` | This segment should be populated with your Redox organization ID. |
| `X` | The second `X` represents the environment type: `0`: development `1`: staging `2`: production |
| `X` | The third `X` represents a number assigned to the partner site. This can be omitted if there’s only one site. |