Assertion: alto clarinet | /r/HasAspect | a half-hole key
Facets:
value: with a vent
type: OTHER
value: usually
type: TEMPORAL
Source sentences:
text: The alto clarinet, however, usually has an extra key allowing it to play a low (written) E♭, and a half-hole key controlled by the left-hand index finger with a vent that may be uncovered to assist in playing the altissimo register.