A detailed analysis of the various possible configurations of the two molecular axes of the HCl and DCl dimers trapped in a monatomic matrix is presented following the ranges of the intermolecular distance. The calculation of the intensity and frequency of the corresponding vibration-orientation absorption bands is performed. Particular attention is paid to the vibrational dependence of the molecular parameters in the solid medium. The consistency of the comparison with the experimental data for the various noble gas solid matrices and for different temperatures and concentrations confirms the interpretation of the spectra following the above analysis. Thus, the existence of intermediate stages called ``pseudodimers'' between the monomer and the dimer is demonstrated. For the ``dimers'', where the molecules are nearest neighbors, the nearly orthogonal configuration previously obtained by the present authors in an a priori calculation of the far infrared absorption is shown to be also suitable.