The encumbrance of landed estate exists relative to main right, which is inevitable to change with the change of main right and have a certain influence on the main right at the same time.

土地他项权利是相对于主权利而存在的，必然会随主权利的变更而发生改变，同时也会对主权利产生一定的影响。

youdao

The distinction made sense when "principal" was a landed estate and "income" was the rent collected from the tenant farmers.

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