# I got a question about the uniqueness of the Reference ID when creating a wallet - what is its use, if another wallet id is created beginning with ewallet\_xxxxx ? Is that just for internal client use?
**URL:** https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410
**Category:** 🙋🏽‍♀️🙋🏽‍♂️ Ask Questions
**Tags:** office-hours
**Created:** [June 10, 2021, 1:14pm UTC](https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410 "2021-06-10T13:14:54Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@drew.harris](https://community.rapyd.net/u/drew.harris)
#### Post date: [June 10, 2021, 1:14pm UTC](https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410/1 "2021-06-10T13:14:54Z")
[SE response] Yes, that’s right. `ewallet_reference_id` is for client use.
Rapyd’s reference to this wallet is through the `id` field (e.g. `ewallet_xxxxx` )
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### Author:  [@drew.harris](https://community.rapyd.net/u/drew.harris)
#### Post date: [June 10, 2021, 1:15pm UTC](https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410/2 "2021-06-10T13:15:44Z")
[Anonymous] So let’s say that username is a unique value in my database. So i can use `ewallet_username` since its always going to be unique
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### Author:  [@drew.harris](https://community.rapyd.net/u/drew.harris)
#### Post date: [June 10, 2021, 1:16pm UTC](https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410/3 "2021-06-10T13:16:32Z")
That’s right.
[SE response] Also note that `ewallet_reference_id` is an _optional_ field while creating a wallet.
[https://docs.rapyd.net/build-with-rapyd/reference/wallet-object#create-wallet](https://docs.rapyd.net/build-with-rapyd/reference/wallet-object#create-wallet)
It’s **optional** but there is uniqueness checking on the Rapyd side
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### Author:  [@CharlesDorsett](https://community.rapyd.net/u/CharlesDorsett)
#### Post date: [June 10, 2021, 1:28pm UTC](https://community.rapyd.net/t/i-got-a-question-about-the-uniqueness-of-the-reference-id-when-creating-a-wallet-what-is-its-use-if-another-wallet-id-is-created-beginning-with-ewallet-xxxxx-is-that-just-for-internal-client-use/410/4 "2021-06-10T13:28:43Z")
Many of the Rapyd processes include some kind of client-defined ID. It is up to the client to determine the format of their own ID. Except as stated below, these are optional and do not have to be unique.
- Payments and refunds - `merchant_reference_id`
- Orders - `upstream_id`
- Checkout page - `merchant_reference_id`
- Payouts and beneficiaries - `merchant_reference_id`
- Wallets - `ewallet_reference_id` - must be unique
- Identity verification `reference_id` - required, and must be unique
- Issued bank account number - `merchant_reference_id`