  Context: Mode identification has remained a major obstacle in the
interpretation of pulsation spectra in rapidly rotating stars.
  Aims: We would like to test mode identification methods and seismic
diagnostics in rapidly rotating stars, using oscillation spectra based on new
theoretical predictions.
  Methods: We investigate the auto-correlation function and Fourier transform
of theoretically calculated frequency spectra, in which modes are selected
according to their visibilities. Given the difficulties in predicting intrinsic
mode amplitudes, we experimented with various ad-hoc prescriptions for setting
these, including using random values. Furthermore, we analyse the ratios
between mode amplitudes observed in different photometric bands.
  Results: When non-random intrinsic mode amplitudes are used, our results show
that it is possible to extract the large frequency separation or half its
value, and sometimes twice the rotation rate, from the auto-correlation
function. The Fourier transforms are mostly sensitive to the large frequency
separation or half its value. When the intrinsic mode amplitudes include random
factors, the results are far less favourable. We also find that amplitude
ratios provide a good way of grouping together modes with similar
characteristics. By analysing the frequencies of these groups, it is possible
to constrain mode identification as well as determine the large frequency
separation and the rotation rate.
