The answer from oracle development on this issue is
"From 126.96.36.199.1, Account, Department and Fund Code chartfields are considered to be mandatory segments and are mapped to three specific dimension tables and their corresponding hierarchy tables given below. These tables are already exposed in the RPD and the customer can use them to do the analysis.
Department – W_COST_CENTER_D – W_COST_CENTER_DH
Fund Code – W_BALANCING_SEGMENT_D – W_BALANCING_SEGMENT_DH
Account – W_NATURAL_ACCOUNT_D – W_NATURAL_ACCOUNT_DH
Since we have separate tables for these now, we have removed them from the list of other chartfields which are populated into a generic table – W_GL_SEGMENT_D"