1 INTRODUCTION  
2 OBSERVATIONS AND DATA REDUCTION  
3 SPECTRUM AND IMAGES  
3.1 ALMA spectrum and molecular identifications  
3.2 SiO and CO line profiles  
3.3 Images  
4 ANALYSIS OF THE LINE INTENSITIES  
4.1 SiO analysis  
4.2 CO analysis  
4.3 Estimating the masses of HCO⁺, SO, CS and SiS  
4.4 Isotopologue ratios  
4.5 Modelling of the CO and SiO line profiles  
5 DISCUSSION  
5.1 Molecular chemistry  
5.2 Line profile and geometry  
5.3 Isotope ratios  
6 CONCLUSIONS