Post 16 education, adult education and further education involve continued study, but a level no different from that found at upper secondary, and are grouped together as ISCED 4, post-secondary non-tertiary education. In the past, those who were disabled were often not eligible for public education. Children with disabilities were repeatedly denied an education by physicians or special tutors. These early physicians (people like Itard, Seguin, Howe, Gallaudet) set the foundation for special education today. They focused on individualized instruction and functional skills. In its early years, special education was only provided to people with severe disabilities, but more recently it has been opened to anyone who has experienced difficulty learning. While considered "alternati