Sentence:  By one o'clock the place was choc-a-bloc. ... The restaurant was packed, and the promenade between the two <WSD>main</WSD> courts and the subsidiary courts was thronged with healthy-looking youngish people, drawn to the Mecca of tennis from all parts of the country. 
Meaning of the word marked with <WSD> tags:  Of chief or leading importance; prime, principal. (from 15th c.)