discarded
How many transitions this element discarded because they had no duration (S§C.11.2).
Two decisions at one instant bound a zero-length interval, which is discarded because a row with no duration carries no information and dividing by its tau is a division by zero. That is not an error — two demands arriving together, each triggering a review, is a correct model — but it is lossy: the earlier decision's action was applied and its transition is never recorded. A non-zero count says the trajectory is lossy at those points and the modeler judges whether it matters.
Readable rather than published: this subsystem adds nothing to a model's report (§10.6).