  The profiles of emission lines formed in the corona contain information on
the dynamics and the heating of the hot plasma. Only recently has data with
sufficiently high spectral resolution become available for investigating the
details of the profiles of emission lines formed well above 10^6 K. These show
enhanced emission in the line wings, which has not been understood yet. Line
profiles of Fe XV formed at 2.5 MK acquired by the Extreme ultraviolet Imaging
Spectrometer (EIS) onboard the Hinode solar space observatory are studied using
multi Gaussian fits, with emphasis on the resulting line widths and Doppler
shifts. In the major part of the active region, the spectra are best fit by a
narrow line core and a broad minor component. The latter contributes some 10%
to 20% to the total emission, is about a factor of 2 broader than the core, and
shows strong blueshifts of up to 50 km/s. On average, the line width increases
from the footpoints to the loop top for both components. A component with high
upflow speeds can be found also in small restricted areas. The coronal
structures consist of at least two classes that are not resolved spatially but
only spectroscopically and that are associated with the line core and the minor
component. Because of their huge line width and strong upflows, it is proposed
that the major part of the heating and the mass supply to the corona is
actually located in source regions of the minor component. The siphon flows and
draining loops seen in the line core component are consistent with structures
found in a 3D MHD coronal model. Despite the quite different appearance of the
large active region corona and small network elements seen in transition region
lines, both show similar line profile characteristics. This indicates that the
same processes govern the heating and dynamics of the transition region and the
corona.
