with a typical duration of a few hundred seconds, alternating with shorter (100-200 seconds) low count rate ($\le$10000 cts/s) periods. In the CD, two separate distributions are seen: during the ‘M’ events HR$_2$ is above 0.1, while in the low-rate intervals it is considerably softer.

$\bullet$ class $\lambda$

:   The observation presented in Belloni et al. (1997a) and a few similar ones constitute class $\lambda$ (Fig. 2m,n): the light curve consists of the quasi-periodic alternation of low-quiet, high-variable and oscillating parts described in Belloni et al. (1997a). In the CD, a C-shaped distribution is evident, with the lower-right branch slightly detached from the rest, and corresponding to the low count rate intervals (typically a few hundred seconds long).

$\bullet$ class $\kappa$

:   Very similar to the previous class are observations in class $\lambda$. The timing structure, as shown by Belloni et al. (1997b), is the same, only with shorter typical time scales (Fig. 2o,p). In the CD, an additional cloud between the two branches is visible (see [@bel97b]).

$\bullet$ class $\rho$

:   Taam, Chen & Swank (1997) and Vilhu & Nevalainen (1998) presented extremely regular RXTE light curves of GRS 1915+105, consisting of quasi-periodic ‘flares’ recurring on a time scale 