A katha (gāthā) is a spoken formula — a short Pali verse said aloud to make something happen. It is the atomic unit of the northern saiyasat: the words a monk or mo chants to protect, to bless, to bind, to heal, to summon. Unlike a genre, a katha is not a kind of book — it is a kind of utterance, and that is exactly why it turns up everywhere. The catalogue holds 179 witnesses whose titles name a katha, and they scatter across the whole collection rather than sitting in one shelf.
The single most important fact about katha is its genre spread. The 179 witnesses fall under buddhist_canonical (55), astrology (44), magic & ritual (28), jātaka (26) and other (18) — no genre owns it, because every genre uses it. The same formula-technology is the recited verse of scripture on one leaf, the efficacious spell of the wichaa on the next. This is the clearest single demonstration of the project's governing thesis: that canonical Buddhism and efficacious saiyasat are one performance seen from two sides. Read this entity as the thread that stitches the chanting liturgy, the astrology and the magic together.
Two registers sit inside the count. On the learned side, the nissaya katha — Nitsai katha thammapata, Panca nibat katha, Thatukatha — Pali verse glossed and parsed for study. On the efficacious side, the sainyasat katha — Katha ongkan (invocation of the Buddha), Katha o, Katha sao hum, the untitled bundles labelled Katha tang tang ("various katha"). The learned katha is read; the efficacious katha is deployed.
Its physical profile breaks the scholastic mould in a telling way. Support is palm-leaf (102) against a very heavy mulberry-paper (75) — far more paper than the canonical or grammar corpora, exactly as one expects of formulae that were opened and used rather than shelved. Script is 92% Tham Lanna but with a notable 19 monolingual Pali witnesses — the katha is Pali, so a share needs no vernacular at all. It reaches back to 1549 and forward to 1974, and 72 of the 179 are flagged research-priority. Holdings lead at Wat Sung Men (38) but spread widely — Wat Si Mongkhon, Wat Lai Hin Luang, Wat Phra That Lampang Luang.
Corpus — this section quotes the contributed printed wichaa textbooks (OCR-digested into the `pages` table), a body distinct from the palm-leaf catalogue the counts above measure. Where the catalogue tells us katha travel bundled and cut across genre, the textbooks show us the thing the title line cannot: what a katha actually does on the page. Citations give slug and page; densest is compendium-of-ancient-katha ("ประมวลคาถาตำราโบราณ", "compendium of ancient katha"), effectively a formulary.
Inference — read together, the textbook rubrics confirm the catalogue thesis from the inside: katha is the operative verb of the wichaa, and its grammar (formula → substance → named effect) is stable enough across these printed books to be treated as a genuine ritual technology, not a loose devotional habit.