CO SLEDs of protocluster members from the literature (full pink circles connected by black lines; Coogan et al. 2018; Casey 2016; Lee et al. 2017, 2019; Gómez-Guijarro et al. 2019) compared with the CO SLED of different types or sources (dotted lines of color as in Fig. 12). Downward pointing arrows indicate upper limits. The protocluster and source names are annotated (see Table C.1). Source names between parentheses are those that do not satisfy the IR luminosity selection criterion.