The text relies on a specific textual variant found in the best manuscripts (A, B) which reads τἀν Διομείοις ('in the Diomeia'), whereas some later editions and conjectures have attempted to emend this to τὰν Διομείᾳ or similar forms. The Dative plural Διομείοις is rare and refers to a specific precinct or festival ground associated with Diomedes, likely in the context of the Argive sanctuary. The phrase describes a location where a certain event (implied by the participle γίγνεται, 'happens' or 'is born') takes place, specifically alluding to the myth of Heracles' birth or a related ritual event at the Diomeia. This construction is syntactically dense, with the relative clause ὁπόθʼ ('whenever') governing the entire locative phrase, requiring the reader to understand the spatial and mythological context of the Diomeia to fully grasp the reference.

The phrase τἀν Διομείοις presents a syntactic curiosity: the article τἀν (ta + tēn) is in the dative plural, modifying Διομείοις, which is itself a plural noun. This construction, where the article agrees with the noun in case and number but the noun is plural while the article is typically singular in such contexts, is rare in Aristophanes and may reflect a specific dialectal or poetic usage. The use of the dative plural here indicates a location 'in the Diomeia,' which is a specific precinct or festival ground, rather than a city or general region. This usage is not standard Attic prose and requires careful parsing to avoid misinterpretation of the spatial reference.

The term Διομείοις (Diomeiois) refers to a specific sanctuary or festival ground associated with Diomedes, a hero from the Trojan War. In the context of Aristophanes' *Frogs*, this location is likely alluding to a mythological event or ritual that is being humorously referenced or parodied. The Diomeia was a known site in Argos, and its mention here may serve to ground the comedy in a specific mythological or local context, adding layers of meaning for those familiar with the cultic and mythological traditions of the region.