成唯識論述記 9.342

9.342

述曰：謂相及性，性者實體，即唯真如；相亦名體，依他體故。有法相對，不明初性，以無體故。

The Commentary states: This refers to mark and nature. 'Nature' is the real substance, which is exclusively tathatā; 'mark' is also called substance, because it is the substance of the other-dependent. When contrasting existing dharmas, the first nature is not clarified, because it lacks substance.