If a provision confers power to make secondary legislation, this attribute will be set to ‘Y’ in all relevant versions. Otherwise it will be set to ‘N’.
Sometimes secondary legislation confers power to make other secondary legislation. This attribute is not set at all in secondary legislation (except, from 2006 onwards, in the case of Northern Ireland Orders in Council that are treated for SLD purposes as primary legislation).
Note that his attribute may not have been set for legislation dating from before the relevant basedate. An exercise to correct this is in progress.