English: Schematic level of a membrane computing system. An outer membrane defines an inner region 1, which in turn surrounds level two membrane regions 2, 3 and 4. Region 4 has three deeper regions 5, 6 and 7, of which region 6 in turn has two deeper regions 8 and 9.

Regions of the same depth share a color.

The transport function at each membrane defines the overall logic of the membrane computer.