  The SPIRE FTS Spectral Feature Finder (FF), developed within the Herschel
Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform
Spectrometer (FTS) instrument team, is an automated spectral feature fitting
routine that attempts to find significant features in SPIRE FTS spectra. The
$^3$P$_1$ - $^3$P$_0$ and $^3$P$_2$ - $^3$P$_1$ neutral carbon fine structure
lines are common features in carbon rich far-infrared astrophysical sources.
These features can be difficult to detect using an automated feature detection
routine due to their typically low amplitude and line blending. In this paper
we describe and validate the FF sub-routine designed to detect the neutral
carbon emission observed in SPIRE spectral data.
