= Payment Processor Account
**Payment Processor** which will handle [[public/payment/partners/apidocs/transaction.init/ | `transaction.init`]] API call is determined based on :
- `ptnr_id` value, which is implicitly known from Authentication Credentials for API call
- `pp_type` parameter in request
By default, these 2 parameters (`ptnr_id` and `pp_type`) further determine **Payment Processor Account** that will be used for transaction.
Depending on exact **Payment Processor** additional request parameters could be used to determine appropriate **Payment Processor Account**:
- **Netbilling** additionally uses `currency` parameter from request (__required__)
- **PayOn** can use `currency` and `bank_country` parameters from request (both are optional)
- **PayU** can additionally use `currency` and `country` parameters from request (both are optional)
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If **Partner** has multiple **Payment Processor Accounts** defined for some **Payment Processor** one and only one of those **Payment Processor Accounts** is chosen depending on exact **Payment Processor**:
- for **Rocket Gate** - **Payment Processor Account** with lowest `ppac_id` value is chosen (first, oldest one)
- for all other **Payment Processor**s - - **Payment Processor Account** with highest `ppac_id` value is chosen (last, youngest one)
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Once we have **Payment Processor Account** determined we know which **Payment Processor** and which **Merchant account** account to use on that **Payment Processor** for **Transaction**.
= Overrides
**Overrides** allow **Partner** to use different **Payment Processor Account** than one which would be determined with default process described above.
Different **Payment Processor Account** also means that completely different **Payment Processor** can be used for **Transaction** (in this case parameter `pp_type` from public/payment/partners/apidocs/transaction.init/ | `transaction.init`]] request is overridden as well).
**Overrides** are activated by passing parameters into [[public/payment/partners/apidocs/transaction.init/ | `transaction.init`]] API call :
- `override` - int, __required__ (for example on #dating this is `company_id`)
- `override_tag` - int, __required__ (for example on #dating this is `site_id`)
- `override_type` - string, optional, recognized values are:
- `''` (empty string, default value) or
- `'x-sale'`
- `currency` - __required__ for `transaction.init` API call
- `ptnr_id` - implicitly known from Authentication Credentials for API call.
These parameters are matched against `overrides` table.
If match is found it will override **Payment Processor Account** that would be used by default.
Match data from `overrides` table will give us
- `ppac_id` - override for **Payment Processor Account** (and consequently **Payment Processor**)
- `force_mid` - when used with **Rocket Gate** it sets appropriate `merchantSiteID` parameter for API call to **Rocket Gate**; when used with **Netbilling** it sets appropriate `processor` parameter for API call to **Netbilling**; otherwise not used.
- `force_acc` - **Rocket Gate** specific, if set it will set appropriate `merchantAccount` parameter for API call to **Rocket Gate**
//Note 1//: if values of both, `override` and `override_tag` parameters are empty (`0` or '' - empty string), then **Overrides** mechanism won't be used, and **Payment Processor Account** will be selected by default (as described in [[ public/payment/overrides/#payment-processor-accoun | Payment Processor Account ]] section on this page).
= Usage in Transaction
Determined **Payment Processor Account** (`ppac_id`), along with other overrides parameters ( `force_mid`, `force_acc` ) is saved into **Order** when making [[public/payment/partners/apidocs/transaction.init/ | `transaction.init`]] API call.
Same **Payment Processor Account** and overrides parameters are then used for next appropriate [[public/payment/partners/apidocs/transaction.finish/ | `transaction.finish`]] API call.
This means that **Transaction** is executed on **Payment Processor Account** determined with process described above.