vs . The one-to-one relation of α_low and α_high is shown with a dashed grey line. The dashed black lines represent spectral indices of zero, dividing the plot in four quadrants (Q1, Q2, Q3, and Q4). The black lines in the corner of each quadrant illustrate the shape of the spectrum. We remind the reader that α is defined as S_ν ∝ ν^−α. Arrows indicate upper or lower limits. In the upper panel, we use LOFAR-IB flux density measurements, while in the lower panel, we use LOFAR6 flux densities and compare them to their position in the upper panel.