By the 4th century, textual "families" or types of text become discernible among New Testament manuscripts. A "text-type" is the name given to a family of texts with similar readings due to common ancestors and mutual correction. Many early manuscripts, however, contain individual readings from several different earlier forms of text. Modern texual critics have identified the following text-types among textual witnesses to the New Testament: The Alexandrian text-type is usually considered to generally preserve many early readings. It is represented, e.g., by Codex Vaticanus, Codex Sinaiticus and the Bodmer Papyri.