CfA spectral sample, providing further evidence that (1) the blue component of the Ca H&K feature is from [Si$\,$]{} $\lambda 3858$ absorption and (2) there is no evidence for a correlation between  and light-curve shape. Finally, we examine the spectra of the well-observed SN 2011fe and SN 2010ae, a very low-velocity SN Iax, in Section \[s:add\]. Although one cannot uniquely claim that the blue component of the Ca H&K profile is from [Si$\,$]{} $\lambda 3858$ for SN 2011fe, it must be the the case for SN 2010ae. We discuss implications of this result and conclude in Section \[s:conc\].

The Ca H&K Line Profile {#s:cahk}
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As noted above, the spectral feature at rest-frame wavelengths of [$\sim\!\!$ ]{}3500 – 4000 Å in SN Ia spectra often has structure such as shoulders and multiple components. The main absorption is thought to be from Ca H&K (from the photosphere and possibly from a HV component) and [Si$\,$]{} $\lambda 3858$. We will refer to this feature as the Ca H&K feature, although there may be additional species contributing to it.

In this section, we will examine the Ca H&K feature in detail. To do this, we use the spectra. After testing their claims of 