The volume was, together with its sister volume, Ups. Gr. 28A, written in the mid 14th c., based on the watermarks and the handwriting (partly in ‘Metochitesstil’). As it is an extensive composite of several autonomous units, it is not unlikely that the production was stretched out over a longer period of time. The following units were, according to Dieter Harlfinger, probably the earliest (1440s): units 1 and 5 in Ups. Gr. 28A together with units 9 and 12 in Ups. Gr. 28B; cf. Karlsson (1981), pp. 24–28. Dieter Harlfinger has suggested that, on the basis of the contents as well as the handwriting, the main scribe is likely to have been a pupil of Thomas Magister and Nicephorus Gregoras; he first proposed that Scribe A might be Demetrius Cydones, in which case we would have a geographical connection to Constantinople. In an addendum, though, this assumption was corrected into an identification of Scribe A as Philotheos Metropolitan of Selymbria (Karlsson (1981), p. 32). This still supports a close connection to the intellectual milieu around Nicephorus Gregoras, to whom Philotheos Metropolitan of Selymbria supposedly was a pupil but later turned against (cf. the anathema preserved in autograph in the Register of the Patriarchate, Vindob. Cod. Hist gr. 47).