Eye chart smaller symbols until the person cannot identify the symbols. The smallest symbols that can be reliably identified is considered the person's visual acuity. The Snellen chart is the most widely used. Alternative types of eye charts include the logMAR chart, Landolt C, E chart, Lea test, Golovin–Sivtsev table, the Rosenbaum chart, and the Jaeger chart. Charts display several rows of optotypes, which are standardized symbols for testing vision. Optotypes are usually letters, numbers, or geometric symbols. Each row of the chart depicts optotypes of a different size. Typically the largest optotypes are in the top row. The optotypes become progressively
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