Structure
Each RSG of the WRB is provided with a listing of possible principal and supplementary
qualifiers, from which the user can construct the second level of the classification. The
principal qualifiers are given in a priority sequence. The broad principles that govern
the WRB class differentiation are:At the first level (RSGs), classes are differentiated mainly according to
characteristic soil features produced by primary pedogenetic process, except
where special soil parent materials are of overriding importance.