Sentence:  Either header sheets or dark-mark coding directly on the answer document itself provides the input to the computer memory for pre-codable information such as test, level, or form, while response spaces to be marked by the user take care of all kinds of unique identifying information, such as community, school, grade, name, sex, and so forth. <WSD>Preslugging</WSD> on a line printer is used for a student identification code. 
Meaning of the word marked with <WSD> tags:  To preprint on a form with automatically-generated individual identifying information.