I have looked at a fuller version of the text you supplied, and it is clear that some indemnity provision has indeed been invoked, though it is not any sort of compensation as such. Rather, one or two of the defendants in PTSC`s consolidated case have invoked a provision for ARM to provide assistance in the litigation.

ARM`s interests are potentially different to, and severable from, those of the original defendants, so ARM have requested a role in the litigation.

The PTSC enthusiasts are getting far too excited over a development that is likely to see PTSC`s case start to crumble. The single patent under which TPL have now (!) claimed infringement by ARM was only filed in 1995, and at that point ARM had a strong history of innovation, and products in the market. If, as I suspect, ARM can show clear evidence that the 584 patent should be invalidated on the basis of prior art, then they can do some serious damage to the case against the other defendants.

No wonder PTSC have gone so quiet. They are obviously wondering what they have got themselves into. The obvious move now would be for PTSC to settle quietly with ARM, and drop the 584 complaint against the original defendants. That might weaken the case overall, but better now than being humiliated at trial.