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Organizations vs. Users
A user can ONLY be attached to several organizations. They can also be removed from the organizations later onone organizations.
If the user is attached to an organization which he currently does not belong to, the user will be removed from the current organization first, and then being attached to the new organization.
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Basically, parent-organization users can manage data at the system scope while child-organization users can only manage data at their organization scope.
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