The Jota nomenclature is much hyped and virtually meaningless.
Slater Bros. converted 3c Triples to 3cE by changing cams, pistons and exhausts, occasionally SFC fork yokes. They then arranged with the Factory the supply of cast wheeled bikes already fitted with the cams and pistons but sans exhaust, from the downpipes back. The Slater collector and resonators were fitted in Bromyard and the result was christened 'Jota'.
Upon the success of the Jota, in competition, and the 140mph road test the name was used on many Laverdas which did not have the "enhancements".
Perhaps the most stark example was the "Jota America", a bog stock 1200, not even a 'Mirage' (a Jotarised 1200).
A Slater letter, for those unfamiliar with Photoshop, is the only "guarantee of authenticity". Maybe, one day in the future, there be a Catalogue raisonné which will remove all doubt, probably.