## 1 Introduction  
Grammar studies usually prescribe explicit rules for the use of a particular grammatical item. The grammatical item under investigation here is _on the contrary_ (hereafter _OTC_) which has been invariably described as a discourse marker of contrast or contradiction by grammar books and dictionaries [1, 2]. The traditional descriptions further highlight the difference between _OTC_ and in contrast (and its variants _by comparison_ and _by contrast_) lies in the presence of negation in the context of the former. For instance, _A Grammar of Contemporary English_[1] describes _OTC_ as an expression that entails **'a denial of the validity** of what preceded by emphasizing that **the opposite** is true' (p. 553), while _by comparison_, _by way of contrast_ and _by contrast_ are used to 'introduce a comparison or contrast without entailing a denial of the validity of what preceded' (p. 554). Similarly, the _Cambridge Advanced Learner's Dictionary_[3], document the common mistake by learners in using _OTC_ as such: 'Use _on the contrary_ to show that you think or feel **the opposite** of what has just been stated. If you are comparing two things and you want to say that the second thing is very different from the first, don't say _on the contrary_, say _by/in contrast_' (p. 304) [with **emphasis added**]. Research on contrastive discourse markers or conjunctive adjuncts specifies the functional role of _OTC_ as that of **correction** or **replacement** [with **emphasis added**]. For instance, in their discussion of adversative relations as one type of conjunctive relations, [PERSON] and [PERSON] [4] identify the special sense of _OTC_ as that of **correction**, which means 'as against what has been said, one formulation is being rejected in favor of another'. In a later work, [PERSON] and [PERSON] [2] describe _OTC_ as a conjunctive adjunct encoding the **replacive** subtype of extension, meaning 'not X but Y', which differs both from the adversative subtype of extension meaning 'X, but conversely Y' and from the concessive subtype of enhancement meaning 'in spite of' (p. 405). [PERSON] [5] also refers to \(OTC\) as a marker of correction, emphasizing that negation is an integral part of \(OTC\) 'only if S1 contains a negation, a continuation in S2 is introduced by \(OTC\), acting as a marker of **correction**' (p. 326). Similarly, [PERSON] [6] describes \(OTC\) as a contrastive discourse marker signaling **corrective** direct contrast between two sentences, where the first sentence constitutes the version of the action or state which is incorrect or inaccurate, in contrast with the second sentence which constitutes an action or state which is correct or accurate. These previous accounts have contributed significantly to understanding \(OTC\)'s use as a contrastive discourse marker that occurs in the context of negative declarative statements, as opposed to the more general contrastive markers, such as _but_ and _however_. However, little is known about the actual use of \(OTC\) in L1 or L2 student writing, and to what extent negation is employed in the replicive sense of the expression. Furthermore, still less is known about the syntactic and semantic features that determine the grammaticality of \(OTC\) in absence of negation in the preceding sentence. To fill these gaps, this study starts from a different perspective in terms of what the empirical data has to say about the use of \(OTC\) in the academic writing of British university-level students represented by British Academic Written English-Essays Corpus (hereafter BAWE-E) [7]. The reliance on the corpus data is central to the distinction between the functional types to be described in this paper. In accordance with [PERSON]'s [8] inductive grammar approach, the syntactic, semantic, and pragmatic parameters of \(OTC\) are identified. Based on careful analysis of the corpus concordance lines, the different functional types of \(OTC\) are accounted for by drawing on thematic analysis [2].