How is Zakah calculated when applied to different categories of wealth (genus)?

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When applying the ruling of encompassing (ad-Damm), Zakah must be taken from each type (jins) of wealth commensurate with what is due from it. Zakah due from one type cannot be taken from another type of wealth. This is because if the ruling of specific assessment applies to sub-types within the same genus, it is more appropriate that it applies across different genera, given their distinct purposes.