Editing Roman numerals (section)

===Specific disciplines===
In [[astronautics]], [[List of orbital launch systems#United States|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 satellite]]s or "moons" of the [[planet]]s are [[Naming of moons#Roman numeral designations|designated]] by capital Roman numerals appended to the planet's name. For example, [[Titan (moon)|Titan]]'s designation is [[Saturn]] {{rn|VI}}.<ref name="jplsats-disc">{{Cite web |date=15 November 2021 |title=Planetary Satellite Discovery Circumstances |url=https://ssd.jpl.nasa.gov/sats/discovery.html |access-date=7 January 2022 |website=JPL Solar System Dynamics |publisher=NASA}}</ref>

In [[chemistry]], Roman numerals are sometimes used to denote the [[group (periodic table)|groups]] of the [[periodic table]], but this has officially been deprecated in favour of Arabic numerals.<ref name="Fluck 1988">{{Cite journal |last=Fluck |first=E. |date=1988 |title=New Notations in the Periodic Table |url=http://www.iupac.org/publications/pac/1988/pdf/6003x0431.pdf |journal=[[Pure and Applied Chemistry|Pure Appl. Chem.]] |publisher=[[International Union of Pure and Applied Chemistry|IUPAC]] |volume=60 |issue=3 |pages=431–436 |doi=10.1351/pac198860030431 |s2cid=96704008 |access-date=24 March 2012}}</ref> They are also used in the [[IUPAC nomenclature of inorganic chemistry]], for the [[oxidation number]] of [[cation]]s which can take on several different positive charges. They are also used for naming [[Phase (matter)|phases]] of [[Polymorphism (materials science)|polymorphic]] [[crystal]]s, 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 {{rn|IX}}" is sometimes seen for "grade 9".

[[File:9th Aero Squadron AEF.jpg|thumb|upright=1.1|Stylised "{{rn|IX}}" represents "9" in unit emblem of [[9th Aero Squadron]] AEF, 1918.]]

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 [[outline (list)#Alphanumeric outline|alphanumeric outline]]. 
* In numbering [[Act of Parliament (United Kingdom)|UK Acts of Parliament]] within a given year (a given [[parliamentary session|session]] until 1963), [[Local and personal acts of Parliament (United Kingdom)#Local acts|local act]]s have lowercase Roman numerals, whereas [[Act of Parliament (United Kingdom)#Public general acts|public act]]s have plain Arabic numerals and [[Local and personal acts of Parliament (United Kingdom)#Personal acts|personal act]]s have [[Italic type|italic]] Arabic numerals.<ref>{{cite web |title=Introduction to Private and Personal Acts |url=https://www.legislation.gov.uk/changes/chron-tables/private/intro#6ListingNumberingandAnnotationsofActs |website=[[legislation.gov.uk]] |access-date=22 July 2024 |page=6. Listing, Numbering and Annotations of Acts}}</ref>

In [[mathematics]] (including [[trigonometry]], [[statistics]], and [[calculus]]), when a graph includes negative numbers, its quadrants are named using {{rn|I}}, {{rn|II}}, {{rn|III}}, and {{rn|IV}}.<ref>{{Cite web |date=2020-08-04 |title=2.1: Definition and Label Quadrants |url=https://math.libretexts.org/Bookshelves/Applied_Mathematics/Calculus_for_Business_and_Social_Sciences_Corequisite_Workbook_(Dominguez_Martinez_and_Saykali)/02:_Cartesian_Coordinate_System/2.01:_Definition__and_Label_Quadrants |access-date=2025-01-31 |website=Mathematics LibreTexts |language=en}}</ref> 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:
* [[movement (music)|Movements]] are often numbered using Roman numerals.
* In [[Roman numeral analysis]], [[Function (music)|harmonic function]] is identified using Roman numerals.
* Individual strings of [[stringed instruments]], such as the [[violin]], are often denoted by Roman numerals, with higher numbers denoting lower strings.

In [[pharmacy]], Roman numerals were used with the now largely obsolete [[apothecaries' system]] of measurement: including {{rn|SS}} to denote "one half" and {{rn|N}} to denote "zero".<ref name="Bachenheimer" /><ref>{{Cite book |last1=Reddy |first1=Indra K. |url=https://books.google.com/books?id=U3QY7gz0C2cC |title=Essential Math and Calculations for Pharmacy Technicians |last2=Khan |first2=Mansoor A. |date=2003 |publisher=CRC Press |isbn=978-0-203-49534-6}}</ref>

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.

[[File:Eire Frankng I-IV-1986.jpg|thumb|Example of postage stamp from Ireland (Éire) franked using Roman numeral for the month]]

In [[team sport|sport]] the team containing the "top" players and representing a nation or province, a [[Sports club|club]] or a school at the highest level in (say) [[rugby union]] is often called the "1st {{rn|XV}}", while a lower-ranking [[cricket]] or [[American football]] team might be the "3rd {{rn|XI}}".

In [[tarot]], Roman numerals (with zero) are often used to denote the cards of the [[Major Arcana]].

In [[Republic_of_Ireland|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 {{rn|LXX}}, as this translation of the [[Old Testament]] into Greek is named for the legendary number of its translators (''septuaginta'' being Latin for "seventy").