Model A's tempoMarking prop is declared but never rendered — a second dead field alongside fingering

A tempo indication (e.g. "Andante", "♩ = 96") is placed above the topmost stave of the first system, in bold plain (non-italic) text, distinct from expressive text.

Gould, Behind Bars, ch. Tempo Indications — placement above the top stave, plain (not italic) bold weight; Ross, The Art of Music Engraving, gives the same placement and weight convention.

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