成唯識論述記 1.268

1.268

離者異義，體異名離，不爾攝計，便為不盡。《瑜伽》四計，即彼後三。雖住蘊中，或住蘊外，或不住蘊，亦非蘊外，並離蘊計。

Separate means distinct: being distinct in substance is called 'separate'; if not, the subsumption of views would not be exhaustive. The four positions in the Yogācārabhūmi are the latter three of those: whether abiding within the aggregates, abiding outside the aggregates, or neither abiding within nor outside the aggregates—all are positions of being separate from the aggregates.