According to Kumarila Bhatta, anupalabdhi (non-apprehension) as the sixth independent source of knowledge consists in the presentative knowledge of

Kumarila's anupalabdhi gives the presentative knowledge of negative facts.

It is admitted as a sixth independent source of valid knowledge.

By it one knows the non-existence of a thing, such as no pot on the ground.

The absence cannot be grasped by perception, which needs a positive object.

Non-apprehension of what would otherwise be seen reveals the negative fact.