Thomas (MJ) came close to stumping me with this one:
I’m going to go with my greatest passion (read: obsession) and say notarization.
But then all of that crazy research I did on the Ptolemaic administration paid off and I recalled reading about ἀγορανόμοι in a Bacchic context. (You can read more about them here and here, and the last site has a bunch of digitized contracts and seals to paw through.)
As it turns out, I was mistaken.
Or at least I couldn’t turn up anything relating to Ptolemaic notaries and Dionysos – however I did find this inscription from Makedonia:
(A) ἔτους αʹ καὶ μʹ καὶ ρʹ Ἀρτεμισίου· | Παράμονος Θεογένους vac. | ἀγορανομήσας τοῦ θιάσου | ἐκ τοῦ ἰδίου Διονύσωι. vac.
(B) τὸ κοινὸν τῶν θιασ|τῶν Παράμονον | Θεογένου.
(A) In the year 141 in the month Artemisios, Paramonos son of Theogenes, having served as market-overseer (agoranomos) of the society (thiasos), set this up for Dionysos from his own resources.
(B) The association (koinon) of society members (thiasōtai) honor with a crown Paramonos son of Theogenes.
Which Phil Harland describes as follows:
Slab of marble, now in the Beroea Museum (inv. no. L 585). There is a framed relief under text A depicting two male figures on either side of an altar. One figure offers a libation while the other holds a scepter in his left hand and a libation cup in his right hand. V. Allamani-Souri identifies the figure on the left as Paramonos and the figure on the right as the god Dionysos (see EBGR 2009, no. 7). Beneath the frame there is a crown with the three inscribed lines of text B on either side. Like many associations, this society adopted a civic title (market-overseer) for one of its internal functionaries.
Further context can be found in the Epigraphic Bulletin:
V. Allamani-Souri, “Σχόλια σὲ μιὰ ἀναθηματικὴ ἐνεπίγραφὴ στήλη ἀπὸ τὴ Βέροια”, in Β΄ Πανελλήνιο Συνέδριο Ἐπιγραφικῆς, p. 31-47 [BE 2011, 408]: A.-S. republishes the dedication to Dionysos by Paramonos, agoranomos of a thiasos, and the honorary inscription of the thiasos for Paramonos (Beroia, 7 BCE; I.Beroia 22; SEG XLVIII 751). On the relief, she identifies the man on the left as Paramonos, and the larger libating male figure on the right as Dionysos. The use of the term θίασος shows that the association was not a professional association of Dionysiac artists, but an association of worshippers of Dionysos. The expression ἀγορανομήσας τοῦ θιάσου means that Paramonos exercised this function in the association (cf. SEG XI 50). The agoranomos of the thiasos was probably responsible for the festival (cf. the expression πανηγύρεως ἀγορανόμος). A dedication of a civic agoranomos to Dionysos is attested in Dion (C. Makaronas, “Νέες εἰδήσεις ἐκ Δίου τοῦ Πιερικοῦ. Ἡ θέσις τοῦ ἱεροῦ τοῦ Διός”, AEphem 1937, p. 529 no. 2: Διονύσῳ καὶ τῷ θιάσῳ Πρι|μίων Φολβίας ἀγορανο|[μ]ήσας ἐκ τ[ῶν ἰδίων]).
Showing that this was not just an isolated incidence of a Dionysian notary.
So, even though I had to resort to Google, I’m gonna count that one as a win too.