> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ionicfi.com/llms.txt
> Use this file to discover all available pages before exploring further.

# IDs

> Prefixed identifiers used throughout the Ionic API.

Ionic uses prefixed, typed IDs. The prefix tells you what kind of object you are holding, and domain validation rejects IDs used in the wrong place.

## Format

```text theme={null}
{prefix}_{base62_suffix}
```

Low-volume objects generally use 14 base62 characters after the prefix. High-volume or security-sensitive objects generally use 24.

## Common prefixes

| Prefix   | Resource                                             |
| -------- | ---------------------------------------------------- |
| `mer_`   | Merchant                                             |
| `cus_`   | Customer                                             |
| `pm_`    | Payment method                                       |
| `pi_`    | Payment intent                                       |
| `ch_`    | Charge                                               |
| `rf_`    | Refund                                               |
| `seti_`  | Setup intent                                         |
| `prod_`  | Product                                              |
| `price_` | Price                                                |
| `pl_`    | Payment link                                         |
| `cs_`    | Checkout session                                     |
| `li_`    | Line item                                            |
| `sk_`    | Secret key ID or secret key prefix context           |
| `pk_`    | Publishable key ID or publishable key prefix context |
| `plat_`  | Platform                                             |
| `pcon_`  | Platform connection                                  |
| `sub_`   | Subscription                                         |
| `si_`    | Subscription item                                    |
| `inv_`   | Invoice                                              |
| `ii_`    | Invoice item                                         |
| `il_`    | Invoice line item                                    |
| `ipat_`  | Invoice payment attempt                              |
| `cn_`    | Credit note                                          |
| `cnl_`   | Credit note line item                                |
| `evt_`   | Webhook event                                        |
| `whe_`   | Webhook endpoint                                     |

## Guidance

* Treat IDs as opaque strings.
* Store the full ID, including prefix.
* Do not infer business meaning from suffix length.
* Validate IDs in your own tests when wiring resources together.