If registered Republican, must vote Republican in the primary.
If registered Democrat, must vote Democrat in the primary.
If registered Independent and there are no Independent candidates, must fill out a Change of Party Affiliation form and either declare a party or register unaffiliated in order to vote in the primary. If there was an Independent candidate, they would need to vote Independent or fill out the Change of Party Affiliation form by the deadline to vote for other than independent candidate.
If Unaffiliated, can vote either Republican or Democrat in the primary. However, political affiliation will become the party that they vote for in the primary and after the primary, they must fill out the Change of Party Affiliation form if they want to go back to unaffiliated or the opposite party.