The count of Arich Anpin proper is the child count that extends Keter Yehuda. It starts at 63 of Keter Yehuda, year ת of Machzor HaGadol, and lasts for 14 (100/7, י''ד) years. Hence, Arich Anpin extends Keter Yehuda with 4 years.
The lower aspect of Arich Anpin is refined first. At the end of the counts of Keter Yosef and Keter Yehuda, this is finalized by the count of Keter Moshe, the Keter of the middle. Keter Moshe is the child count contained by Keter Yehuda. It starts at 59 of Keter Yehuda, year צ of Machzor HaGadol, and also lasts for 14 years.
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