This book is the first in-depth corpus-based study to present a unified model of both Linear Unit Grammar and Linear Unit Discourse Analysis. To illustrate this model, the book focuses on the role of discourse reflexivity in the linear structure of online message board discourse from the Internet Movie Database (IMDb) webpage. It is shown that discourse reflexivity plays a central role in the linear structure and antagonism characteristic of this type of discourse. This book will particularly appeal to those who have an interest in carrying forward the innovations in the description of grammar, lexis and discourse proposed by John Sinclair in his lifetime as well as to those with a specific interest in discourse reflexivity and computer-mediated communication.