Non-identical rests on a shared stave are displaced vertically by voice role, by roughly one staff space, clear of the opposite voice's noteheads

When two voices sharing a staff do NOT have identical simultaneous rests, each voice's rest is displaced away from the shared middle-line default position — the upper (up-stem) voice's rest raised by about one staff space, the lower (down-stem) voice's lowered by about one staff space — enough to clear the other voice's noteheads and stems at that beat. This one-space default is the convention shared across major engraving programs' 'two-voice rest offset' tables (Finale and Sibelius both default to a one-space shift for quarter, eighth, and sixteenth rests in two-voice contexts; whole and half rests shift a comparable amount), not one specific numeric figure asserted by a single treatise.

A rest whose fixed vertical position sits inside or touching the other voice's notehead, ledger line, or stem at that same beat — possible under Gradus's current scheme because the offsets are FIXED per role regardless of what the other voice's actual pitch is doing at that instant.

Gould, Behind Bars (general rest-clearance principle, same chapter as the shared-rest rule below); Ross, The Art of Music Engraving, ch. on rests, states the clearance requirement without prescribing one universal offset — practice varies by how far the opposing voice's notes actually reach; the one-staff-space figure is corroborated by Finale's and Sibelius's documented default two-voice rest positions.

This rule needs the notated content and the rendered result together — the score says what should happen, the page says whether it did.