It means the Separatists led by Count Dooku (or Darth/Lord
Tyrannus) such as on Geonosis in episode 2.
And yes Anikan/ Darth Vader was Luke Skywalker's father.
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In Star Wars, CIS stands for the Confederacy of Independent
Systems, which were called the Seperatists, who were trying to
succeed from the Galactic Republic.
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Confederacy.
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A loosely organized group of independent states with a weak
central government is a confederacy.
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A voluntary association of independent states is a
confederacy.