Articulations (staccato, accent, tenuto, marcato, fermata) mostly need NO horizontal spacing term — but must not be summed like accidentals when stacked

Unlike accidentals or dynamics, articulation glyphs are centered directly on the notehead's own x-position rather than needing dedicated clearance before or after it; most articulation glyphs are narrower than or comparable to a notehead. The one outlier is fermata, whose glyph is visibly wider than a notehead. Gould and Ross both place articulations as vertical, not horizontal, spacing concerns except at extreme note density.

This is a MISSING rule in the original draft of this chapter, which enumerated accidentals/dots/ledger-lines/grace-notes/ornaments/dynamics as attachments needing width but never addressed articulations at all — an omission worth stating explicitly given articulations are one of the eight `MelodyNote` attachment fields (line 60). Gradus's code (lines 1014-1022) attaches articulations via VexFlow's `Articulation` modifier with no width reservation anywhere, which for MOST articulation types is actually CORRECT (no width reservation needed) rather than a bug — but if a future width accumulator is built (as several other rules in this chapter recommend) and an implementer naively applies the accidental-stacking pattern (spacing-chord-accidental-stacking) to articulations, that would be a NEW bug: articulations on one note stack VERTICALLY (staccato dot above tenuto line above fermata), not horizontally, so their widths must never be summed the way stacked accidentals are.

Gould, Behind Bars, articulation chapter (articulations sit directly above/below the notehead, vertical stacking not horizontal spread); Ross, The Art of Music Engraving (articulation clearance is a vertical-collision problem, addressed in the beam/slur-avoidance chapter, not the horizontal-spacing chapter); SMuFL/Bravura glyph metrics measured directly from Gradus's own font dependency, which quantify this precisely.

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