-# form selectbox for show_voided_credits:
-# - value='': use default from $conf
-# - value="0" : override default, do not show voided credits
-# - value="1" : override default, show voided credits
+# form checkbox for show_voided_credits:
+# - value=unset : do not show voided credits
+# - value="1" : show voided credits