all spanners supporting line-interface:
	DynamicTextSpanner
	Episema
	Glissando
	Hairpin
	HorizontalBracket
	LigatureBracket
	OttavaBracket
	PianoPedalBracket
	TextSpanner
	TrillSpanner
	TupletBracket
	VoiceFollower
	VoltaBracket

spanners supporting line-interface AND line-spanner-interface:
	DynamicTextSpanner
	Episema
	Glissando
	TextSpanner
	TrillSpanner
	VoiceFollower

spanners supporting line-interface but NOT line-spanner-interface:
	Hairpin
	HorizontalBracket
	LigatureBracket
	OttavaBracket
	PianoPedalBracket
	TupletBracket
	VoltaBracket

line-interface properties:
	arrow-length
	arrow-width
	dash-fraction
	dash-period
	style
	thickness
	zigzag-length
	zigzag-width

line-spanner-interface properties:
	bound-details
	extra-dy
	gap
	left-bound-info
	note-columns
	right-bound-info
	simple-Y
	thickness
	to-barline

ottava-bracket-interface properties:
	edge-height
	bracket-flare
	shorten-pair
	minimum-length