In Johnson v. Howells, 682 P.2d 504 (Colo. App. 1984), a division of this court interpreted a covenant very similar to the one at issue here. There, the division held that the covenant was plain in its meaning: barring unanimous agreement, it could not be amended within the initially designated time period. To interpret the covenant otherwise, the division reasoned, "would be to render meaningless the reference therein to the initial twenty-year period. If the owners had intended that the covenants could be amended at any time . . . they would not have needed to include any reference to a twenty-year period." Johnson v. Howells, supra, 682 P.2d at 505.