The smallest unit to be annotated are still sentences, even though in principle individual clauses may fit better with CoreSCs and reduce the overlap in annotations.
we decided against the annotation of clauses, as recently employed clause recognition algorithms seem to be purpose-built for specific application areas (e.g (Del Corro and Gemulla, 2013) or (Kanayama and Nasukawa, 2012)) and prior built clause detection mechanisms performed with Fmeasures up to 78.63% (Tjong et al., 2001), which in itself could introduce noise to the task of automatically identifying CoreSC concepts.