Zoom-in on the magnesium (in the left column) and silicon K-edge (in the right column). The HEG and MEGdata are respectively shown in light and dark grey. The solid red line represents the best fit whose dust composition is specified in Table 3. Bottom panels: residuals defined as (data − model)∕error. The data are stacked and binned for display purposes. For GRS 1915+105 we only display observation ID 7485, which also shows photoionisation lines (see Appendix A for further details).