Instituta Patrum de modo psallendi is a High Medieval document, allegedly based on circulated precepts of Bernard of Clairveaux, and perhaps other church figures as well. It enjoins church communities to sing psalm tones in a certain way.
The first half of a psalm verse is to be sung in one breath, followed by a pause to catch breath. Then the second half of the verse is to be "deponendus" to the psalm tone's musical cadence, where "deponere" here means lowering the music in pitch from its psalm tone 'tenor' to its final pitch by a 5- or 6-note cadence:
Facta pausa, quod de versu restat, morosiori modulatione deponatur salvo tono.
The pause having been made, let what remains in the verse be laid down to/by the safe(?) tone with slower mensuration.
Salvo tono? What does that mean? How is one to read this sentence, assuming there is no typo or missing word?