136 Francis G. H. Pang 2.2 Stanley E. Porter (1989) Porter shares many methodological assumptions with McKay; he also stresses the distinction among aspect, Aktionsart, and temporal reference. To him, tense-form only reflects the speaker’s conception of the action (aspect), it is not used to grammaticalize time or Aktionsart. However, aspect may relate to other contextual factors (deictic indicators) to express temporal reference at the level of pragmatics36. As mentioned above, Porter builds his aspectual theory on a systemic functional linguistic paradigm37. Three points are stressed in his model: (1) Aspect is a matter of semantics; (2) the Greek verbal structure is viewed as system-based and (3) Aspectuality is treated as one of the two major systems in the Greek verbal network. Within this aspectual system, there are three individual aspect-systems: perfective (Aorist), imperfective (Present/Imperfect) and stative (Perfect/Pluperfect). In Porter’s system, the Future form is considered an anomaly due to its odd formal paradigm and limited distribution38. It is treated as partially aspectual with the choice of [±expectation] and grammaticalizes a speaker’s expectation toward a process39. The semantic value of each of these aspect-systems can be described in terms of verbal opposition. Marked pairs are used to describe these alternatives on the basis of equipollent binary opposition. Within the aspectual system40, at the least delicate level, the system requires choice of [+expectation] or [+aspectual] to distinguish the partial aspectual choice (Future) with the full aspectual choices. Further to the right with choices of greater delicacy are the two sub-systems ASPECT 1 and ASPECT 2, both full aspectual choices which cover the Aorist, Present and Perfect41. The aspect of the Pluperfect and Imperfect is realized by combining the ASPECT 2 with the REMOTENESS [±remoteness] system under [+assertion]. The following is part of the systemic display of the Greek verbal network42: 36 Decker, Temporal Deixis, 22. 37 Porter, Verbal Aspect, 7-16. 38 Porter, Idioms, 43. Porter contends that these peculiarities of the Future form can be explained by its late development in Greek verbal structure and thus independence of the form in relation to the rest of the network. Porter, Verbal Aspect, 95. See below for more detail. 39 More on this in the next section. See also, Porter, Verbal Aspect, 93-7 and 409-16. 40 For a more developed version of the Greek verbal network, see S.E. Porter and M.B. O’Donnell, “The Greek Verbal Network Viewed from a Probabilistic Standpoint: An Exer- cise in Hallidayan Linguistics”, FgNT 14 (2001) 40. 41 For detail, refer to Porter, Verbal Aspect, 89-109, esp. 93-6. 42 Part of chart 4 in Porter, Verbal Aspect, 109.