When i select bolt material by CII flange application,
There are 3 allowable cases for SA-193 B7 material.
(occurrence 1,2,3)

It looks like giving difference allowalbe as per class/thickness, and ASME Sec II specify size/thickness.

I know no idea about class/thickness or size/thickness.
So, Please kindly let me know how to define occurrence 1,2,3 in CII.