al. 1999).

On the basis of this analysis, Belloni et al. (1997a,b) tentatively concluded that the variability of GRS 1915+105 consists of oscillations between two separate states: state corresponds to an accretion disk extending all the way down to the innermost stable orbit and therefore appears always with the same spectral colors, while state corresponds to different portions of the inner disk being unobservable, and therefore can be found in different regions of the CD, but always at lower count rate and always separated from state . However, Belloni et al. (1997b) also noticed that, although this characterization could be applied to most observations available at the time, one type of observation could not be reduced to these two states. This type observation is class $\theta$ in our classification of light curves (see Section 2). A typical observation of this class is shown in Fig. 6. The light curve consists of M-shaped intervals reminiscent of the long state segments in Fig. 4. (although at a much higher flux level), alternated with low-rate stretches. In the middle of these low-flux stretches there are some ‘flares’. Comparing the CD in Fig. 6 with that in Fig. 4, we can see that it 