UnitySubsystemsManifest.json contains metadata about your provider that can be queried before your plug-inA set of code created outside of Unity that creates functionality in Unity. There are two kinds of plug-ins you can use in Unity: Managed plug-ins (managed .NET assemblies created with tools like Visual Studio) and Native plug-ins (platform-specific native code libraries). More info
See in Glossary is loaded. The values in this dictionary are used to populate specific instances of SubsystemDescriptors in C#. For example, information within the displays list is used to populate XRDisplaySubsystemDescriptors.
For Unity to find the a native library referenced by the UnitySubsystemsManifest.json file, the library must be no more than two subfolders deeper than the UnitySubsystemsManifest.json file.
Example .json file:
{
    "name": "PluginName",
    "version": "1.0.0",
    "libraryName": "UnityXRDisplayExample",
    "displays": [
        {
            "id": "Display0",
            "supportedMirrorBlitReservedModes" : ["leftEye","rightEye", "sideBySide"]
        }
    ],
    "inputs:": [
        {
            "id": "MockHMD Head Tracking Stationary"
        },
        {
            "id": "MockHMD Head Tracking Simulated"
        }
    ]
}
| Metadata | Description | 
|---|---|
| name | The name of your provider. Must match the first parameter of your native plug-inA platform-specific native code library that is created outside of Unity for use in Unity. Allows you can access features like OS calls and third-party code libraries that would otherwise not be available to Unity. More info See in Glossary’s RegisterLifecycleHandlercall. | 
| version | Unused currently. | 
| libraryName | Must match the name of your provider’s native plug-in binary without the extension. | 
| displays | Collection of Display subsystem providers. | 
| id | Identifier for this display plug-in configuration. The idmust match the string you pass into your native plug-in’sRegisterLifecycleHandlercall for that subsystem. You can have more than onedisplay, as long as your native plug-in callsRegisterLifecycleHandlerfor each. | 
| inputs | Collection of Input subsystem providers. | 
Your manifest file can include additional fields for a display record after id - subsystems specify which parameters are valid.