1. A system-on-chip apparatus, the apparatus comprising: a scan path comprising at least a first hierarchical level, the first hierarchical level comprising a plurality of components and a second hierarchical level comprising at least one component, wherein data is propagated within the first hierarchical level using at least one control signal applied to the components of the first hierarchical level; and control logic adapted for filtering application of the at least one control signal to the at least one component of the second hierarchical level in a manner for controlling propagation of data within the second hierarchical level independent of propagation of data within the first hierarchical level.