This diagram illustrates the hierarchy used in a CGNS dataset to define
a single boundary condition.
At the top level is a box labeled "BC", representing the boundary
condition.
At the next level are:
- a "BC patch specification" box
- a "BC type (compound)" box
- multiple "BC data set" boxes numbered from 1 to N
Below each "BC data set" box are the following three boxes.
- "BC type (simple)"
- "Dirichlet BC data"
- "Neumann BC data"
Below the "Dirichlet BC data" box are two boxes labeled with the Greek
letters alpha and beta, and below the "Neumann BC data" box are two
boxes labeled with the Greek letters gamma and delta.