Dynamic text validated against a closed vocabulary on ALL THREE surfaces

A dynamic marking is one of a closed set of conventional abbreviations (ppp…fff, fp, sf, sfz, fz, rfz, sffz per Gould) rendered in bold italic serif type — never arbitrary prose.

Gould, Behind Bars, ch. Dynamics — dynamics are always one of the standard italic abbreviations, never spelled-out words like "loud"; Read, Music Notation, similarly restricts the sanctioned symbol set.

This rule can be decided from pitches, durations and voices — no layout required. A validator can check it before anything is drawn.