Upper limit of the onset of disk substructures. Same as Figure 1, but the bolometric temperature was derived from the SED fitting without the Herschel Space Observatory data (70–500 µm) (Dunham et al. 2015). Extinction correction was applied to the infrared data, which further increased the bolometric temperature (Dunham et al. 2015). The effective resolution and the ALMA Band 6 1.3 mm flux of protostellar disks are color-coded and shown in different symbols according to the presence or absence of substructure. Compact disks with diameters smaller than four beams are indicated by crosses. The black arrow is used to indicate that the particular source has also been classified as Class II in the literature (Narayanan et al. 2023).