成唯識論演祕 7.199

7.199

釋曰：遍計體無，為境能起依他執心，名「轉有體」。「轉」猶起也。由依他性能起依他，名「有轉有」。是所執依，名「轉於無」。

The commentary states: The parikalpita is devoid of substance, yet serving as an object, it is able to give rise to the grasping mind of the paratantra, hence it is called 'transforming what has substance.' 'To transform' is like giving rise to. Due to the paratantra-nature being able to give rise to the paratantra, it is called 'the existent transforming the existent.' Serving as the basis for what is grasped, it is called 'transforming the non-existent.'