There are two types of workflows that can be created/managed:

Action Workflows (for future reference, action workflows will be referred to as workflows): they are visible and can be executed from Portal if active
Snippet workflows: they allow users to reuse predefined sets of actions in workflows. They are not designed to be executed in Portal, but triggered to be executed when the linked workflow's execution reaches the Start Snippet Workflow activity. All workflows that will be created/imported under category Snippets will be considered snippet workflows.

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