Sentence:  There was another day when Paul W. Litchfield, president of the Goodyear Tire and Rubber Company, came to see him. Litchfield was thoroughly disturbed, because he had heard that Knudsen wanted Goodyear's trademark—a yellow and blue <WSD>houseflag</WSD>—left off all tires sold to Chevrolet. 
Meaning of the word marked with <WSD> tags:  Flag that identifies a company, unit, or group.