In the top-level README for bilara-data, toward the end there’s an explanation of references:
The reference files contain detailed references to over a dozen editions of the Pali canon. These were originally collated by the Dhamma Society for their Mahsaṅgīti edition, and have been supplemented by SuttaCentral.
The full forms of the abbreviations may be found in
pali_edition.json.
Where can I find pali_edition.json? The text is not linked, and I poked around a bit but didn’t find it.