成唯識論演祕 4.668

4.668

據等無間六皆名意，今目第六，故為不然。五識根別，依根立名，無濫可爾。

According to the immediately preceding [condition], all six are called 'manas'; here, referring specifically to the sixth, it is therefore 'not so'. The faculties of the five consciousnesses are distinct; establishing their names based on the faculties involves no ambiguity, and hence 'can be so'.