section_path: Modern use/Specific disciplines
section_name: Specific disciplines
paragraph_text: Specific disciplines
  
  In astronautics, United States rocket model variants are sometimes designated by Roman numerals, e.g. Titan I, Titan II, Titan III, Saturn I, Saturn V.
  
  In astronomy, the natural satellites or "moons" of the planets are designated by capital Roman numerals appended to the planet's name. For example, Titan 's designation is Saturn VI.
  
  In chemistry, Roman numerals are sometimes used to denote the groups of the periodic table, but this has officially been deprecated in favour of Arabic numerals. They are also used in the IUPAC nomenclature of inorganic chemistry, for the oxidation number of cations which can take on several different positive charges. They are also used for naming phases of polymorphic crystals, such as ice.
  
  In education, school grades (in the sense of year-groups rather than test scores) are sometimes referred to by a Roman numeral; for example, "grade IX " is sometimes seen for "grade 9".
  
  In entomology, the broods of the thirteen- and seventeen-year periodical cicadas are identified by Roman numerals.
  
  In graphic design, stylised Roman numerals may represent numeric values.
  
  In law, Roman numerals are commonly used to help organize legal codes as part of an alphanumeric outline.
  
  In mathematics (including trigonometry, statistics, and calculus), when a graph includes negative numbers, its quadrants are named using I, II, III, and IV. These quadrant names signify positive numbers on both axes, negative numbers on the x-axis, negative numbers on both axes, and negative numbers on the y-axis, respectively. The use of Roman numerals to designate quadrants avoids confusion, since Arabic numerals are used for the actual data represented in the graph.
  
  In military unit designation, Roman numerals are often used to distinguish between units at different levels. This reduces possible confusion, especially when viewing operational or strategic level maps. In particular, army corps are often numbered using Roman numerals (for example, the American XVIII Airborne Corps or the Nazi III Panzerkorps) with Arabic numerals being used for divisions and armies.
  
  In music, Roman numerals are used in several contexts:
  
  In pharmacy, Roman numerals were used with the now largely obsolete apothecaries' system of measurement: including SS to denote "one half" and N to denote "zero".
  
  In photography, Roman numerals (with zero) are used to denote varying levels of brightness when using the Zone System.
  
  In seismology, Roman numerals are used to designate degrees of the Mercalli intensity scale of earthquakes.
  
  In sport the team containing the "top" players and representing a nation or province, a club or a school at the highest level in (say) rugby union is often called the "1st XV ", while a lower-ranking cricket or American football team might be the "3rd XI ".
  
  In tarot, Roman numerals (with zero) are often used to denote the cards of the Major Arcana.
  
  In Ireland, Roman numerals were used until the late 1980s to indicate the month on postage Franking. In documents, Roman numerals are sometimes still used to indicate the month to avoid confusion over day/month/year or month/day/year formats.
  
  In theology and biblical scholarship, the Septuagint is often referred to as LXX, as this translation of the Old Testament into Greek is named for the legendary number of its translators (septuaginta being Latin for "seventy").