Segments are considered to be hierarchically- organised so that they may be temporarily suspended during an interrupting subsegment. Within a segment it is assumed that standard techniques of computational linguistics can be applied. The main difficulty lies in identifying transitions between segments. The discourse followed a plan structure to assemble the pump, with segments corresponding to components of the plan. Cue phrases signal the intentional structure of the discourse.
Discourse analysis involves the identification of such relationships between sentences and segments.
RST describes text structure in terms of 'nuclei' and 'satellites'. The nuclei refer to the main ideas or goals of the writer. The satellites provide various kinds of support for the nuclei. This support may be an example, an elaboration, a reason, and so on. The top-most schema organises the text as a whole, with subschemata providing a hierarchical structure to the text.