楞伽阿跋多羅寶經註解 1.611

1.611

論其種性本無差別，無始熏習，或內或外、或大或小、或定或不定。此經所以明夫種性有五言無間者，謂其種性純一無間雜也。

Speaking of their gotras, they are originally without differentiation, but due to beginningless perfuming, they are either internal or external, either Mahāyāna or Hīnayāna, either determinate or indeterminate. The reason this sūtra clarifies that there are five gotras and speaks of 'unhindered' is to say that their gotra is pure, unified, and without interruption or mixture.