an increase in core principal quantum number — $1s\rightarrow 2s$ or $\left\{2s,2p\right\}\rightarrow\left\{3s,3p,3d\right\}$ — giving the dominant dielectronic capture into the low-$n<10$ resonances. Even following core radiative stabilization, these low-lying states are impervious to collisional reionization for the range of densities $x\le 10$, and thus we set $S^N(x,q,T)=1.0$ for $N=\left\{1,2,10\right\}$. However, at densities $x> 10$, the @summersRAL data for these three isoelectronic sequence show suppression factors that are fit well by the usual Eq. \[eqsuppression2\], so we do not modify $S^N(x,q,T)$ for these cases.

Lastly, we consider the intermediate isoelectronic sequences for which excitation arises from neither a fine-structure splitting of the ground state nor a change in principal quantum number of the core. These include the Li-like $2s\rightarrow 2p$, Be-like $2s^2\rightarrow 2s2p$, N-like $2s^22p^3(^4S)\rightarrow 2s2p^4(^4P)$, Na-like $3s\rightarrow 3p$, Mg-like $3s^2\rightarrow 3s3p$, and P-like $3s^23p^3(^4S)\rightarrow 3s3p^4(^4P)$ cases up through the third row sequences. Any large low-temperature DR contribution arising from near threshold resonances is to low-lying states, for which suppression is negligible, i.e. the high-temperature suppression factor must be switched-off ($S^N \rightarrow 1$) at low-$T$.

To illustrate the general demarcation between low-$T$ and high-$T$ DR, we first consider DR of , an overview of which is depicted in Fig. \[fig4\]. The 