In this example, the edge (d0, c1) has a buffer.

Each buffer has a priority, that
is a positive natural number. 
The buffer size and initial 
volume are expressed in hours 
of the model's capacity unit. 
The initial volume holds on
the run start date at 00:00.

The virtual buffers at source and sink have fixed priorities 0 and |buffers|+1, respectively. They have infinite size.

Taken together, the buffer priorities must be a permutation of 0 .. |buffers|+1. In the context of the changing network constraints, this permutation fixes the buffer operating tactics:

• the buffers get filled in order of high to low priority; high priority buffers get filled first
• they get emptied in order of low to high priority; low priority buffers get emptied first

The buffer operations are ignorant of the future.