How is arc resistant low voltage switchgear rated? What are the performance characteristics of the ratings?

IEEE C37.20.7 established the following performance ratings that must be listed on the apparatus rating label:

• Accessibility 
  • Type (example – Type 2B) 
    • Type 1 (Arc-resistant functionality in the front of the equipment only) 
    • Type 2 (Arc-resistant functionality in the front, rear and sides of the equipment only)
  • Optional accessibility type performance features (accessibility type suffixes)
    • “A” suffix (Arc-resistant provided all enclosure doors and covers are closed and secured) 
    • “B” suffix (Arc-resistant provided all enclosure doors and covers are closed and secured; except control/auxiliary compartment doors which can remain open)
    • “C” suffix (Arc-resistant functionality in compartments adjacent to the compartment in which the arc occurs). This suffix isn"t applicable for metal-enclosed low voltage switchgear. IEEE C37.20.7 – 2007 states that the “C” suffix designation isn"t applicable to equipment using open bus or open frame construction. All metal-enclosed low voltage switchgear uses an open bus design. · 
    • “D” suffix (A modification of Type 1 in which one or more of the enclosure surfaces is excluded from the arc-resistant category. For example, Type 1D-SR would indicate a design which arc-resistant functionality on the front and right side only, with the rear and left side considered inaccessible to personnel). 
• Maximum internal arcing short-circuit current 
• Maximum system voltage 
• Maximum arcing duration