+=item cust_bill_pkg_detail [ CLASSNUM ]
+
+Returns the list of associated cust_bill_pkg_detail objects
+The optional CLASSNUM argument will limit the details to the specified usage
+class.
+
+=cut
+
+sub cust_bill_pkg_detail {
+ my $self = shift;
+ my $classnum = shift || '';
+
+ my %hash = ( 'billpkgnum' => $self->billpkgnum );
+ $hash{classnum} = $classnum if $classnum;
+
+ qsearch ( 'cust_bill_pkg_detail', { %hash } ),
+
+}
+