  As part of the first high resolution far-IR spectral survey of the Orion KL
region (Lerate et al. 2006), we observed 20 CO emission lines with Jup=16 to
Jup=39 (upper levels from approx 752 K to 4294 K above the ground state).
Observations were taken using the Long Wavelength Spectrometer (LWS) on board
the Infrared Space Observatory (ISO), in its high resolution Fabry-Perot (FP)
mode (approx 33 km s$^{-1}$). We present here an analysis of the final
calibrated CO data, performed with a more sophisticated modelling technique
than hitherto, including a detailed analysis of the chemistry, and discuss
similarities and differences with previous results. The inclusion of chemical
modelling implies that atomic and molecular abundances are time-predicted by
the chemistry. This provides one of the main differences with previous studies
in which chemical abundances needed to be assumed as initial condition. The
chemistry of the region is studied by simulating the conditions of the
different known components of the KL region: chemical models for a hot core, a
plateau and a ridge are coupled with an accelerated Lambda-iteration
(ALI)radiative transfer model to predict line fluxes and profiles. We conclude
that the CO transitions with 18<Jup<25 mainly arise from a hot core of diameter
0.02 pc and a density of 10$^{7}$ cm$^{-3}$ rather from the plateau as previous
studies had indicated.
