A tie's curve must clear ledger lines and staff lines, not cross them

A tie arc must not visually intersect a staff line or ledger line it passes near; engravers nudge the curve's height/width outward specifically to clear these.

A tie between two notes close to (but not on) a staff line, especially notes with several ledger lines, can render with an arc that visually crosses a ledger line if VexFlow's default tie curvature isn't wide enough for the note's ledger-line count.

Ross discusses adjusting tie curvature to avoid staff-line collision as a routine hand-engraving task; Gould's general clarity principle applies (no notation element should be obscured by or obscure a staff line).

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