The above NIP relies on POS service suppliers and defines three new events that compose Trade support.

## Building blocks

The following 4 building blocks enable trading products over Nostr.

### POS Service Supplier

A web service that allows setting up a single product sell page. Preferably with lightning, as it integrates well with Nostr.

A POS supplier url can be part of a Product event allowing redirecting users to a buy page of the product supplied by the POS service.

### Product Event

A new special event of kind xx that describes a purchasable product.

### Product Purchase Event

A new special event of kind xx+1 describes how to purchase a product. This event links a POS service supplier to the product.

Keeping the method of purchasing separated from the product allows changing POS suppliers with no effect on product data, rating, and reputation.

### Rating Event

A new special event of kind xx+2 that describes ratings assigned by a Nostr user to a product.