Here is something from Schneider electric that may help.
“Typically a 200A Individual Meter Socket is rated 200A CONTINUOUS and is suitable for use with 80% Rated Main Breaker Load Centers Rated 250A maximum. Square D does not make a standard 80% Rated 250A Main Breaker Load Center, but does offer 80% Rated 225A Main Breaker Load Centers having a total connected load restricted to 180A that is less than 200A continuous rating listed above.
Other common Individual Meter Socket frame sizes include:
100A continuous = 125A Max Main Breaker Load Center that is rated for a total connected load of 80% [125A x 0.80 = 100A].
200A continuous = 250A Max Main Breaker Load Center that is rated for a total connected load of 80% [250A x 0.80 = 200A].
320A continuous = 400A Max Main Breaker Load Center that is rated for a total connected load of 80% [400A x 0.80 = 320A].
400A continuous = 500A Max Main Breaker Load Center that is rated for a total connected load of 80% [500A x 0.80 = 400A].”