This method avoids overlooking the decimal separator, which may not be rendered reliably on components or when duplicating documents.
The letter R was chosen because visually it loosely resembles the Ω glyph, and also because it works nicely as a mnemonic for resistance in many languages.
Similar, the standard prescribes the following lowercase letters for capacitances to be used instead of the decimal point: p (for 10−12), n (for 10−9), μ (for 10−6), m (for 10−3), but uppercase F (for 100 = 1) for farad.
[20][21] Though non-standard, some manufacturers also use the RKM code to mark inductors with "R" indicating the decimal point in microhenry (e.g. 4R7 for 4.7 μH).
G, J, K, M) were already used in US military contexts following the American War Standard (AWS) and Joint Army-Navy Specifications (JAN) since the mid-1940s.
[33] Some manufacturers specify a three-character date code with a two-digit week number following the year letter.
[nb 9] For resistances following the (E48 or) E96 series of preferred values, the former EIA-96 as well as IEC 60062:2016 define a special three-character marking code for resistors to be used on small parts.
The code consists of two digits denoting one of the "positions" in the series of E96 values followed by a letter indicating the multiplier.