  Spectroscopic analyses of Type Ia supernovae have shown there exist four
spectroscopic groups---cools, broad line, shallow silicon, and core
normal---defined by the widths of the Si II features at 5972 Angstroms and 6355
Angstroms. 1991bg-likes are classified as "cools". Cools are dim, undergo a
rapid decline in luminosity, and produce significantly less nickel than normal
Type Ia supernovae. They also have an unusually deep and wide trough in their
spectra around 4200 Angstroms and a relatively strong Si II absorption
attributed to the line at 5972 Angstroms. We examine the spectra of supernova
(SN) 1991bg and the cools SN 1997cn, SN 1999by, and SN 2005bl using the highly
parameterized synthetic spectrum code SYNOW, and find general agreement with
similar spectroscopic studies. Our analysis reveals that this group of
supernovae is fairly homogeneous, with many of the blue spectral features well
fit by Fe II. The nature of the spectroscopic commonalities and the variations
in the class are discussed. Finally, we examine intermediates such as SN 2004eo
and discuss the spectroscopic subgroup distribution of Type Ia supernovae.
