Mont. Code Ann. § 3-5-502

Each clerk of court in each county of the respective judicial districts of the state shall keep, in addition to the records required by law, an index called "General Index--Plaintiffs" and also a second index to be called "General Index--Defendants". Each index shall be in a form determined by the clerk to best fulfill the needs of the court and other users of the index and shall contain, at a minimum, those entries required by 3-5-503.