The voters of a charter county may reserve in the charter the power of referendum by which they may submit a local law enacted by the county council, by petition, to the voters for approval or rejection. The charter shall specify: what types of local laws may be petitioned to referendum; and whether a part of a local law may be petitioned to referendum. Subject to paragraph (2) of this subsection, in implementing procedures that relate to the power of referendum, the charter or the local laws shall provide adequate details as to time, notice, and form. The initial notice of a referendum vote shall be given at least 30 days before the election.