Sentence:  <WSD>Preliminary</WSD> data from 1959 Eta give an average impact rate of * * f for masses larger than * * f for about 1000 events in a 22 - day period ( LaGow and Alexander , 1960 ) . 
Meaning of the word marked with <WSD> tags:  denoting an action or event preceding or in preparation for something more important; designed to orient or acquaint with a situation before proceeding