Vocal score conventions — piano reduction in cue size

In a vocal score, the piano-reduction stave is engraved in cue size (roughly 70-80% of the vocal stave's notehead/text size) to visually subordinate it as a rehearsal aid, and it condenses the orchestral texture rather than duplicating the vocal line.

Not representable — Gradus has no accompaniment-reduction concept; every voice renders at the same notehead size. MODEL GAP, relevant only if a vocal-plus-piano-accompaniment format is added.

Gould (Behind Bars, vocal score conventions, cue-size guidance); Ross (standard vocal-score cue-size ratios).

This rule is about where marks land on the page, so it can only be judged after engraving. Collision and spacing faults live here.