Sentence:  Its 50 H-7 2-8-8-2's (30 of which found their way onto the Union Pacific <WSD>roster</WSD> in 1945) were simple mainly because a tunnel in the Alleghenies would not accommodate the low-pressure cylinders of any Mallet larger than a 2-6-6-2. 
Meaning of the word marked with <WSD> tags:  A list of individuals or groups, usually for an organization of some kind such as military officers and enlisted personnel enrolled in a particular unit; a muster roll; a sports team, with the names of players who are eligible to be placed in the lineup for a particular game; or a list of students officially enrolled in a school or class.