SN 2014J spectrum around the K I 7665Å line showing different measured continua by increasing the node separation from top left to bottom right: 250, 400, 600, 750, 950, and 1150 km/s. The black line is the spectrum, the blue lines are the estimated flux errors, the red stars are the nodes and the red dashed line is the continuum crossing the nodes. Red dotted lines represent the continua at ±25% of the node separation being considered. The grey-shaded area is the integrated line within ±600 km s⁻¹. The dashed vertical line is the central wavelength of the line.