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"Posted" means uploaded to the Platform. "Release" is synonymous with "Post".
"Published" (for something posted) means to be made available to all Platform users.
"Downloadability" is a Dataset attribute separate from whether it's "Published" (though in practice a Dataset is Posted, then Published before it's made downloadable).
A Dataset is associated with a Project in one of two ways, (1) it is accessible by a Group created for a project team, (2) it is used in a Workflow owned by the Project. The latter is the definition of a Project "using" a dataset.
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