Sentence:  Hard surface cleaning in household application is represented by two classes of alkaline products : ( 1 ) the formulations made expressly for machine dishwashers , and ( 2 ) the general-purpose cleaners used for <WSD>walls</WSD> and woodwork . 
Meaning of the word marked with <WSD> tags:  an architectural partition with a height and length greater than its thickness; used to divide or enclose an area or to support another structure