Assertion: stringed instrument's string | /r/HasProperty | perpendicular
Facets:
value: to the keys
type: OTHER
value: to the soundboard
type: OTHER
Source sentences:
text: In the harp family (including the lyre), the strings are perpendicular to the soundboard and do not run across it.
text: The mechanism and strings in upright pianos are perpendicular to the keys.