Cohesion: Marking Textual Transitions And Manipulating Textual Statuses

Halliday & Matthiessen (2004: 586-7):

Cohesion includes

1. the system of conjunction for marking textual transitions in the unfolding text and 
2. the systems of reference, ellipsis and substitution, and lexical cohesion for manipulating textual statuses of elements in the flow of information.