<P> In 1988, Jack Stenner and his associates at MetaMetrics, Inc. published a new system, the Lexile Framework, for assessing readability and matching students with appropriate texts . </P> <P> The Lexile framework uses average sentence length, and average word frequency in the American Heritage Intermediate Corpus to predict a score on a 0--2000 scale . The AHI Corpus includes five million words from 1,045 published works often read by students in grades three to nine . </P> <P> The Lexile Book Database has more than 100,000 titles from more than 450 publishers . By knowing a student's Lexile score, a teacher can find books that match his or her reading level . </P> <P> In 2000, researchers of the School Renaissance Institute and Touchstone Applied Science Associates published their Advantage - TASA Open Standard (ATOS) Reading ease Formula for Books . They worked on a formula that was easy to use and that could be used with any texts . </P>

Which of the following is not important for readability