Sentence:  How explicit such factors have been historically <WSD>is</WSD> evident in any chronology of restrictive covenant cases or in a review of NAREB 's Code of Ethics Article 34 in the Code , adopted in 1924 , states that `` a Realtor should never be instrumental in introducing into a neighborhood a character of property or occupancy , members of any race or nationality , or any individuals whose presence will clearly be detrimental to property values in that neighborhood '' . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)