Sentence:  Scarcity of paper caused many Southerners to adopt the practice of cross writing , i. e. , after writing from left to right of the page in the usual manner , they gave the sheet a half turn and wrote from end to end across the <WSD>lines</WSD> previously written . 
Meaning of the word marked with <WSD> tags:  text consisting of a row of words written across a page or computer screen