Tremolo/repeat beams are not representable in Gradus's schema

Measured tremolo notation uses short unattached beam strokes across a stem (or between two stems) to indicate rapid repetition rather than a rhythmic beam group.

N/A as an authorable fault — a capability-boundary note. Tremolo is essentially absent from Gradus's curriculum scope (species counterpoint, chorale harmony, fugue, figured bass, ear training, kid mode) so this is low priority.

Gould, Behind Bars, ch. Beaming/Tremolo — repeat-beam (tremolo) notation as a distinct beaming convention from ordinary rhythmic beaming.

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