Unlike a standard node in a Bayesian network, a temporal node may require more than one distribution. To understand why, it is useful to unroll a dynamic Bayesian network, and look at the equivalent Bayesian network.

A dynamic Bayesian network
Temporal Distributions Before
The dynamic Bayesian network above unrolled for 5 time steps
TemporalDIstributions After

The distributions required for the dynamic Bayesian network are shown below.

AP(A[0])At time 0, node A has no incoming links
AP(A[0]|A[-1])At time 1, node A has a single incoming link from A at time 0
AP(A[0]|A[-2], A[-1])At time 2 or more, A has two incoming links from A at time-1, and A at time-2
BP(B[0]|A[0])At any time, B has a single incoming link from A at the same time