How does Get-InstalledPSResource detect packages installed from a repository?

[ahinterl]

I wonder how Get-InstalledPSResource detects packages that were installed from a repository when browsing $env:PSModulePath.

The cmdlet returns a PSResourceInfo object with a RepositorySourceLocation property that's set to https://www.powershellgallery.com/api/v2 in my case.
Get-Module returns a similar PSModuleInfo object with the same property.

On my computer, RepositorySourceLocation is $null for the psreadline module included in PowerShell.

Is RepositorySourceLocation the criterion to decide whether a package was installed from a repository?

[ThomasNieto]

There is a hidden xml file created in each of the installed module directories created when the module is installed.