  Knowledge of the geometry of pulsational modes is a prerequisite for seismic
modelling of stars. In the case of slowly pulsating B-type (SPB) pulsators, the
simple zero-rotation approach so far used for mode identification is usually
not valid because pulsational frequencies are often of the order of the
rotational frequency. Moreover, this approach allows us to determine only the
spherical harmonic degree, $\ell$, while the azimuthal order, $m$, is beyond
its reach. On the other hand, because of the density of oscillation spectra of
SPB stars, knowledge of $m$ is indispensable if one wants to assign the radial
order, $n$, to the observed frequency peaks. Including the effects of rotation
via the traditional approximation, we perform identification of the mode
angular numbers ($\ell,~m$) for 31 SPB stars with available multicolour time
series photometry. Simultaneously, constraints on the rotational velocity,
$V_{\rm rot}$, and the inclination angle, $i$, are determined assuming uniform
rotation and a constant value of $V_{\rm rot}\sin i$. Dependence of the results
on the adopted model is tested using HD\,21071 as an example. Despite some
model uncertainties and limitations of the method, our studies show the correct
approach to identifying the low-frequency oscillation modes.
