The definition of learning disabilities varies and may include not only reading disabilities and dyslexia but also problems with spoken language, writing, or reasoning ability. Because NLS is a service for blind and physically handicapped individuals, all applications must be based on a visual or physical handicap, including applications accepted under the terms "learning disabilities" (the broader term), "dyslexia," or "reading disability." The certifying authority, as defined by Public Law 89-522—which governs the program—must determine that the reading disability prevents reading regular print in a normal manner and must be medically able to judge whether the disability has a physical or organic basis. For more information about learning disabilities and the program, refer to the factsheet Talking Books and Reading Disabilities available on the NLS website at www.loc.gov/nls or by calling 1-888-NLS-READ.