Assertion: proscenium | /r/HasProperty | surrounded on side
Facets:
value: usually
type: TEMPORAL
value: by a physical proscenium arch
type: OTHER
Source sentences:
text: A proscenium (Greek: προσκήνιον) is the metaphorical vertical plane of space in a theatre, usually surrounded on the top and sides by a physical proscenium arch (whether or not truly "arched") and on the bottom by the stage floor itself, which serves as the frame into which the audience observes from a more or less unified angle the events taking place upon the stage during a theatrical performance.