HRDs showing the large-scale magnetic properties of JH 223 and other classical and weak-line T Tauri stars. CTTSs are labeled by name. Symbol size scales with the average magnetic field strength, color with the poloidal magnetic energy fraction, and shape with the fraction of poloidal energy in axisymmetric modes. Evolutionary tracks (black lines) and isochrones (green dotted lines) from Baraffe et al. (2015) are shown, together with the fully convective boundary and the 40% radiative-core mass limit (dashed blue lines). Magnetic field data for the T Tauri stars are taken from Donati et al. (2014, 2015), Yu et al. (2017), Hill et al. (2017), Nicholson et al. (2018), Hill et al. (2019), Yu et al. (2019), Nicholson et al. (2021), Xiang et al. (2023), Donati et al. (2007, 2008, 2010a,b, 2011a,b, 2012, 2013, 2019, 2020a), Zaire et al. (2024), Donati et al. (2026).