Eye chart number). The denominator indicates the distance in feet at which a person with normal vision could stand to correctly identify the same symbols identified by the person tested. For example, a visual acuity of 20/20 is considered normal. Numerous types of eye charts exist and are used in various situations. For example, the Snellen chart is designed for use at 6 meters or 20 feet, and is thus appropriate for testing distance vision. There is often also a need to test a subject's vision at near or occupational tasks (such as reading or computer use). For these situations, a Rosenbaum
Superior letter o, r, s, and t. In English, however, 'h' is also sometimes rendered as a superior letter, as in 6th. In French, certain abbreviations are written with the first letter(s) of the word they represent, followed by the final letter(s) in superscript. The superscript in this case is sometimes optional. Most commonly, this appears in the abbreviations of personal titles: "M" (or "Mgr") stands for "monseigneur" ("Your Grace"), "M" (or "Mlle") for "mademoiselle" ("Miss"), "M" for "maître" ("Mr"), etc. Other abbreviations containing superior letters are "m" for "merchandise" ("merchandise"), "éch" for "échéance" ("due date"), and "M" for "métro" ("subway"). When