Examples of diverse line profiles of observed class I methanol emission at 84 GHz (upper panel) and 95 GHz (lower panel), depicting narrow maser-like features (panel a), broad thermal-like features (panel b) and a combination of the two (panel c). The line profiles of the two transitions are sometimes quite similar (panels a to c) and sometimes very different (panels d to f). The frequency and the corresponding quantum numbers of each transition are shown in the upper right corner of each panel for six sources. The horizontal magenta dashed lines in G36.90−0.41 and G37.48−0.10 represent the 3σ noise level for the undetected transitions.