Repetition, as measured by type-token ratios (Biber 1988), identifies the students' shifts in discourse features, from the level of morphology and lexicon to that of rhetorical strategy and macroproposition.

In electronic discourse, repetition and allo-repetition most often signal alignment and politeness with regard to other writings, other writers. Emulation at the clausal, sentential and rhetorical levels signals stance and injects affect (Tannen 1989).

Word-level tagging enabled us to look more closely at type-token ratios (TTR) for successive segments to see what and how a specific writer signalled at lexical, syntactic or rhetorical levels when shifting. These shifts were purposeful, though students were seldom aware of their occurrence; they were consequential, as they presented new topics, new frames, or new styles available for challenge, emulation or affiliation.

In electronic conferences, particularly when text is keyboard-composed (as opposed to off-line, uploaded text, or synchronous messaging), students repeat, quote, or allude to texts by others at multiple levels, frequently within the same message. The discourse blends characteristics of both conversation and writing (Davis and Brewer, forthcoming 1977: Ch 1; Baldwin, 1996).

When placed on the kinds of continuums established by Biber (1988), electronic discourse presents features of both informational and involved text. This kind of discourse sounds conversational, but it is written; in the absence of backchannelling and other cues from oral or signed discourse, its writers adapt conversational strategies to express themselves in writing. Its pervasive repetition is different, for example, from what Johnstone establishes to distinguish conversation from informative discourse. In informative discourse , she notes, repetition "takes the form of lexical repetition or pronominalization, whereas conversational discourse has larger elements repeated....repetition may have a more narrowly cohesive function in informative discourse, as opposed to a more interactional, collaborative function in conversation" (Johnstone 1995, vol 1, p. 18).

Writers in electronic conferences employ both functions, but not always in the same ways that such functions appear in conversation.

In reviewing functions of repetition, particularly in oral disourse, Johnstone notes, "One function of repetition is to preface or to express disagreement. That is, if you take a position and I repeat your position, one function of my repetition is to preface that I am getting ready to disagree with you, or perhaps the repetition itself constitutes disagreement with you. The closer the repetition is to identical, the closer it often is to direct disagreement" (Johnstone 1995, vol 1, p. 7).

In asynchronous electronic discourse, however, the usual function of direct, unmarked repetition and allo-repetition at the level of word or phrase is to signal the writer's appropriation and concomitant adherence, agreement, or alignment. Quotation becomes a case of the writer's using punctuation to mark deliberate, conscious repetition, which then can scaffold either agreement or disagreement. We use the term "emulation" to refer to the appropriation or imitation of elements and patternings above the word-level in written utterances.