Answer: We asked who before he retired was one of the most knowledgeable election law experts in Colorado. He was unaware of this.
Starting in November 2010, Initiated Statutes are assigned numbers beginning with 100, restarting at 100 after 199, and instead of calling the measure an Initiative it is called a Proposition. See Colorado Revised Statutes, Title 1, Article 5, Section 407; Article 40, Section 115; Article 40, Section 124.5and Colorado Constitution, Article V, Section 1, ¶ 7.5
The director of research for the Colorado legislative council uses these new numbers in the Blue Book, an impartial voter information pamphlet with an abstract of the fiscal impact study and arguments for and against the measure.