---
# System prepended metadata

title: Instrument

---

# Instrument
Owners of social activity or an initiative with a social aim, such as non-profit organizations, associations, or private individuals, can register as an **WOM Instrument** and be added to the list of WOM Instruments that can generate vouchers and reward contributors.

## What you can do
As a WOM Instrument, you can reward your service's users by generating WOM vouchers. Instruments generate WOMs in the form of *URL* (represented as a QRCode or a deep link) and a *Password*. Users awarded with WOMs can obtain their vouchers by means of the WOM Pocket App.
Through the WOM Pocket, users redeem their vouchers (and secure them in their WOM Pocket), scanning a QRCode (or following a deep link) and typing the associated password.

## What you need
* An Instrument Id (in the form of a GUID, usually assigned by the WOM Platform once registered);
* An Instrument Private Key (locally available as  PEM file, assigned by the WOM Platform);
* One or more AIM codes. One Instrument is enabled to generate WOMs marked with specific AIM codes.
* The geographical location associated with each WOM to be generated. 
* A date and time to be associated with each WOM.
* The number of WOMs to be generated.


# Merchant / POS
A **Point of Service (POS)** is a technical end-point managed by a **Merchant**. A POS allows Merchants to issue payments and to collect vouchers.

## What you can do
By means of a POS a Merchant can issue new **Payment Requests**. A Payment Request allows Merchants to be paid by voiding existing user vouchers.
There are two different kinds of Payment Request. They can be **ephemeral** or **permanent**.
**Ephemeral Payment Requests (EPRs)**, can be used for just one payment, they became invalid afterward. EPRs are typically used for online transactions, or anytime the details of a WOM Payment need to be tailored to meet specific requirements.  
**Permanent Payment Requests (PPRs)** are static payment means which can be used for multiple (possibly unlimited) payment transactions. 
PPRs are typically used to sell fixed-price services and goods.

## What you need
* A POS Id (in the form of a GUID, usually assigned by the WOM Platform once registered);
* A POS Private Key (locally available as  PEM file, assigned by the WOM Platform);
* The number of vouchers requested as payment for a service or a good.
* Optionally, a **Filter** to limit the kind of vouchers which can be used to pay. Filters can be comprised of one or more of the following elements:
     * The vouchers' maximum age. E.g., Vouchers older than 7 days can't be accepted.
     * A geographical (rectangular) bounding box. Only Vouchers earned within the specified area are allowed.
     * An Aim code to filter out vouchers earned volunteering towards other public aims.
* Optionally, an HTTPS end-point for receiving payment acknowledgments.
