  We present a comprehensive study to determine if the LINER/H II region
transition spectrum in NGC 4569 can be generated solely by photoionization by
the nuclear starburst. A review of the multiwavelength data from the literature
reveals no additional sources that contribute to the ionization. We find that
the young starburst dominating the UV emission is distinct from the nuclear
population of A supergiants identified in the optical spectrum by Keel (1996).
Spectral synthesis analysis provides constraints on the physical nature of the
starburst, revealing a 5-6 Myr, approximately instantaneous starburst with
subsolar metallicity. These results are used to model the spectral energy
distribution of the ionizing continuum. Luminosity constraints place limits on
the steepness of the extinction curve for the young starburst. The Savage &
Mathis (1979) curve satisfies all luminosity constraints and the derived
reddening is similar to the emission line reddening. These results imply
extreme conditions in the nuclear starburst, with ~5x10^4 O and B stars
compacted in the inner 9" x 13" region of the nucleus. Using photoionization
analysis and employing all observational constraints on the emission line gas,
we find very specific conditions are required if the spectrum is generated
solely by stellar photoionization. At least two spatially distinct components
are required - a compact region with strong O III emission and an extended, low
density component emitting most of the S II flux. A high density component is
also needed to generate the O I flux. Additionally, a limited contribution from
Wolf-Rayet stars to the ionizing SED is necessary, consistent with the results
of Barth & Shields (2000). We present a physical interpretation for the
multi-component emission line gas.
