located close to the long quiet interval. The assumption underlying this division is that the three long quiet intervals are indeed single intervals of no variability. Notice that our $\chi_1$ and $\chi_3$ intervals correspond to the “plateau” states in Fender et al. (1999). Figure 10 illustrates a selection of four observations in this class. It can be seen that the position in the CD is similar to that associated to state (see the previous section), and we therefore conclude that class $\chi$ is an example of state only. The absence of flares and visible quasi-periodicities, as well as the presence of variability in the form of white noise at time scales of 1 second (see Markwardt, Swank & Taam 1999 and Trudolyubov, Churazov & Gilfanov 1999), further supports this identification as the same state as the low flux periods described in Section 3.2. However, it is clear that there is substantial spectral variability between different observations, as the clouds of points in the CD are found in quite different positions (Fig. 10). As mentioned in Section 3.2, for shorter events, the position of state is also variable. In order to examine these variations, we computed the average values of the 