Same as Figure 5 but for the chemical composition of CO3. Each scaling mass (magenta lines) corresponds to the WD mass (from right to left, 0.55–﹩1.2\,{M}_{\odot }﹩ by ﹩0.05\,{M}_{\odot }﹩ steps, except ﹩0.98\,{M}_{\odot }﹩), the same as those tabulated in Table 1 (CO3). The thick magenta lines of equi-M_sc (or equi-M_WD) correspond to the WD mass region for CO novae (﹩{M}_{\mathrm{WD}}\leqslant 1.05\,{M}_{\odot }﹩).