Sentence:  A semi-serious literary document entitled `` The Wings of Henry James '' <WSD>is</WSD> noteworthy , if only for a keenly trenchant though little-known comment on the master 's difficult later period by modest Owen Wister , author of `` The Virginian '' . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)