strengths.

There is a clear spectral progression as the temperature changes. We note that for [SYNOW]{}, $T_{\rm bb}$ only changes the continuum shape of the models and does not affect the strength of features. Since [SYNOW]{} uses Ca H&K as the reference calcium line, the strength of the Ca H&K absorption by definition does not change much with $T_{\rm exc}$, and the entire calcium spectrum does not change much over the temperatures probed. Meanwhile the [Si$\,$]{} spectrum changes significantly with varying $T_{\rm exc}$. The strength of the Ca H&K absorption within the Ca H&K feature (i.e., the strength of the red component) does change slightly with $T_{\rm
  exc}$ because of the strength of the [Si$\,$]{} $\lambda 3858$ emission changing the apparent Ca H&K absorption.

In the red, there is the expected change in the ratio of the [Si$\,$]{} $\lambda 5972$ and $\lambda 6355$ lines. This ratio, $\mathcal{R}$(Si), is highly correlated with luminosity and light-curve shape [@Nugent95]. As the [Si$\,$]{} $\lambda
5972$ feature becomes stronger, the [Si$\,$]{} $\lambda 3858$ feature becomes weaker. For the [SYNOW]{} models, $\mathcal{R}$(Si) increases with increasing $T_{\rm exc}$, while for SNe Ia, $\mathcal{R}$(Si) increases with decreasing $T$; this has been previously noted [e.g., @Bongard08], and is likely 