Orion/Documentation/Developer Guide/Plugging into the settings page
Orion plugins can define settings. A setting defines some persistent information that is provided to one of the plugins's services. Defined settings appear on Orion's Settings page, and their values can be changed using an automatically-generated UI. Each setting has a unique identifier called a PID (persistent identifier), as well as metatype information. The metatype defines the "shape" of the setting, specifically what named properties appear in the setting and what data type they have (string, boolean, number, etc). The Settings page uses this metatype information to generate appropriate UI widgets (for example, text field, checkbox, etc).
Contributes a setting.