Who can Vote in Indiana's Primiary?

It has been awhile since I read Matthew Tully's Indianapolis Star column but Open primary opens the door for crossover vote caught my eye:

"And that brings us to the recent uproar over whether Republicans, or independents who have voted in recent GOP primaries, can vote in the Democratic presidential primary."

The answer is yes. All one needs to do to vote in an Indiana primary is to be a registered voter. Not something that has been made clear to me all these years, but then I never thought about voting but one way in a primary.