of our observation intervals can be seen as boundary cases between two classes. Therefore, our classification is not intended to exhaustively list mutually exclusive modes of behavior for GRS 1915+105 as: (i) transitions between some classes exist, (ii) a smaller number of classes would probably be sufficient to describe our observations, and (iii) more classes probably exist. The point of our work will instead be to demonstrate that this very complex behavior in fact follows a few very simple “universal laws”. Summarizing, in Fig. 3 we show a histogram with the “occupation times” of the different classes in our sample. Noice that class $\chi$ is by far the most common.

Classes $\lambda$, $\kappa$ and $\theta$: the basic states
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Two observations representing classes $\lambda$ and $\kappa$, I-38-00 (Interval \#3) and K-33-00 (Interval \#2) respectively (notice the shortened naming convention, explained in the caption to Table 1), have already been presented by Belloni et al. (1997a,b). For a better understanding of what follows, we will briefly summarize their main result, restated using the terminology that we will use throughout the rest of this work. Let us start with examining class $\lambda$. The total light curve, the CD and the HID are 