Figure 6 shows the R dependence of the ratios N_{Si-O-Al}/N_{Si}, N_{NBO}/N_{Si} (p = 1) and N_{NBO}/N_{Si-O-Al} for the standard model of aluminosilicate glass.  The ratio N_{NBO}/N_{Si} for the GYZAS model of magnesium aluminosilicates with p = 0.77 is also given. The ratios are calculated for tie-lines with either 50 mol% silica (left column) or 60 mol% silica (right column).