What is a Spectrum?
  This contribution describes the "spectro-perfectionism" algorithm of Bolton &
Schlegel (2010, PASP, 122, 248) that is being implemented within the Baryon
Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey III
(SDSS-III), in terms of its potential to deliver Poisson-limited sky
subtraction and lossless compression of the input spectrum likelihood
functional given raw CCD data.
