Sounds like it is describing a split bus panel with a main for each section to me.
Kwired gets the cookie.:thumbsup:
Here is the panel statement for the 2008 rule change:
Panel Statement: The panel has reworded the exceptions to maintain as much
continuity as practical with prior code practice. Exception No. 1 is based on
current 408.36(B) Exception, which is intended to recognize a long standing
practice of allowing a small panel to be used as service equipment, with large
line-to-line loads leaving at this point and a smaller feeder entering the building
to supply what formerly was called a lighting and appliance branch circuit
panelboard.
The limitations now to be built into this exception prevent the
extension of this limited practice to what could otherwise become a split-bus
panelboard of unlimited size in the future. The six-circuit limit echoes the
customary service limitation in 230.71.
Exception No. 2 corresponds to the parent language in 408.36(A). Since prior
practice effectively limited these panelboards to 42 circuits, the wording in the
panel action carries that limitation forward, but only for these split-bus panels.