Representative string length (top panel) and phase dispersion (bottom panel) diagrams for the star V2689 Ori. The black line denotes the computed L_n and Θ_n for I_{H α}, respectively. The red line denotes L_n and Θ_n for I_Ca,1, respectively. The blue dashed horizontal line denotes the 1% FAP level below which a period would be significant. The arrows mark the photometrically measured period of 12.02 days (Kirkpatrick et al. 2012) and multiples.