Diagram of the energy levels for A-type (left) and E-type (right) methanol transitions covered by ALCHEMI. The x-axis gives the quantum number K, while the number for each level gives J. The transitions used in the analysis are indicated with a color code corresponding to ALMA bands, as given in the top right corner. The maser candidate lines are presented as dashed lines, with their frequency in GHz. We note the energy difference of 7.9 K between the ground state of A and E-type.