Indiana Code Title 3. Elections § 3-10-1-31.3

Sec. 31.3. (a) This subsection applies to a primary election within an election district in which more than one (1) political party chooses the party's nominees or in which a nonpartisan ballot is available for a voter to vote for an office or on a public question. A voter whose political party is not recorded on the poll list as required under section 24 of this chapter shall be shown on the voter's registration record as having cast an unknown ballot in that primary.

(b) This subsection applies to a primary election within an election district in which only one (1) political party chooses its nominees and a nonpartisan ballot is not available. A voter:

shall be shown on the voter's registration record as having cast a ballot for the political party choosing that political party's nominees in that primary election.