This means that, ideally, we would like every utterance to contain a single phrase. However, due to the nature of the SWB data, we realize that this is not always possible. The previous instructions take precedence over this one. The end of the preceding utterance coincides with the start of the next utterance. Hence all data is accounted for.
Segmentation essentially involves placing a boundary between two utterances.
Consider a stretch of silence which has small amplitude noises embedded in it as a silence only utterance - do not mark the noise and do not segment the noises into separate utterances. However, if a noise has a particularly high amplitude, then segment it into its own utterance. Follow the dictionary on hyphenating compounds in clear-cut cases. Contractions are allowed. Use normal capitalization on proper nouns.