# Schemata

You can use an aCheck QR code however you wish. Typically they're added to documents such as test reports, certificates and event tickets. For each use case, you must define a Schema.

A Schema is the collective name for the following:

* Schema ID. The unique reference for a Schema.
* Schema name. A name to identify the Schema.&#x20;
* Original Data Supplier. The name for the value generating entity. A medical testing laboratory for example.
* Expiry policy. The period of time that the QR code's web page will be available for viewing when scanned. Define a date or a duration.&#x20;
* Logo image. A logo for the Original Data Supplier.
* The name of each field that has a value assigned to it when a QR code is created. aCheck has up to 5 fields for Original Data values to be assigned for each QR code. You can define any label for each field. For example, First name, Age or Date of Birth etc.

New Schemas are created without an expiry policy. Please choose the Schema from the Home page to define the expiry policy. You cannot use a Schema that does not have an expiry policy.

All you Schemas can be found on the Home page

