Passing the River is the one script among Agrippa's three angelic alphabets built specifically around Hebrew rather than around whichever language a practitioner happens to be writing: its twenty-two characters answer one for one to the twenty-two letters of the Hebrew alphabet, Aleph through Tav, in the traditional Hebrew order, so a text written in Passing the River is Hebrew rendered in an alternative letterform rather than Latin or a vernacular language written in disguise. This distinguishes it structurally from Celestial and Malachim, which both cipher the Latin alphabet and can therefore be used to write any language ordinarily set down in Roman letters.
The Latin name, Transitus Fluvii, crossing of the river, has no settled explanation in the surviving scholarship on the script; it may allude to a specific biblical crossing, most plausibly the Israelites' crossing of the Jordan, though Agrippa's own text does not spell out the connection explicitly enough for the reference to be treated as certain, and the honest position is that the name's precise meaning remains an open question rather than a documented fact.