ibc table 503 construction types a and b

huangyhg

ibc table 503 construction types "a" and "b"
what do the "a" and "b" represent at the top of table 503 in the international building code?
they are just two alternative "types" of construction.  each has different requirements regarding heights and areas.  so you might have a type iiia construction or a type iiib, each with different provisions.