Single-pixel continuum-subtracted spectra extracted toward the peak position of the compact methyl formate sources in the ALMA-IMF protoclusters. The spectra are shifted along the y axis and the value in parentheses (if any), indicates the scaling factor applied to the spectrum. The vertical dashed lines show the velocity range used to compute the methyl formate moment 0 maps as in Fig. 2. The red horizontal dotted lines show the 3σ threshold, using the rms noise level measured in the line cubes (see Table 2). The figure continues on the next page.