What is the limitation in iOS called that restricts the number of external apps that can be called?

I remember iOS limiting the number of appURLs that can be listed in an application. This is to prevent any app from enumerating sensitive apps the user may have installed.

  • What is this feature called?

  • Does this apply when calling deeplink URLs? e.g. if the limitation applies to 20 URLs, what happens when I call the 21st URL?

  • What is the correct way to link to additional URLs, when I don't necessarily need to know if the application is installed?