All dynamics in one system share a single baseline; they are not each individually centered under their own note's height

Dynamics across a system are drawn at one consistent y (the baseline for that staff's dynamics row), regardless of whether the notes above them are high or low in the staff.

Two dynamic marks in the same system (one under a high note, one under a low note) render at different y heights.

Gould, Behind Bars, ch. 'Dynamics'; one of the more universally agreed conventions across Gould/Ross/Read, matching every major engraving program's default behavior.

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