In Project Export Settings > Resources, what's the difference between "Export", "Bundle", and "--"?

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:bust_in_silhouette: Asked By user41420082
:warning: Old Version Published before Godot 3 was released.

When I go to Project Export Settings > Resources and set Export Mode to Export Selected Resources (including dependencies), I can pick from the drop down on the right. What do these three mean?

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I also want to export the PCK without the dependencies, how do I do that?