{"schemaVersion":1,"slug":"iec-odd-parity-element","name":"IEC odd-parity element","kind":"symbol","abbreviation":"2k+1","aliases":["odd-number-active element","2k+1 qualifier element","odd parity gate"],"category":"logic-signals","drawingTypes":["Schematic"],"referenceFamilies":["IEC","Manufacturer"],"summary":"Element marked 2k+1 that is active when an odd number of inputs are active, as used for parity.","description":["The 2k+1 qualifier means the output is active when an odd number of inputs are active. It is what a cascade of two-input exclusive-OR gates actually computes, and it is the correct IEC qualifier for an odd-parity tree drawn as a single element.","Drafters converting older drawings sometimes mark a multi-input parity tree as =1. That is wrong under the IEC meaning, because =1 requires exactly one active input. Replacing it with 2k+1 removes the ambiguity.","The element does not indicate the number of data bits on its own; show the full input set or a grouped bus with its width."],"readingNotes":["Do not read 2k+1 as exactly one active.","Check whether the result is used as odd or even parity downstream."],"drawingChecklist":["Use 2k+1 for multi-input parity trees.","State the word width.","Reference the parity convention used by the protocol or memory."],"distinction":"The =1 element gives the same result only for two inputs.","facts":[{"label":"Qualifier","value":"2k+1 (odd number active)"},{"label":"Two-input equivalent","value":"Exclusive-OR"},{"label":"Artwork scope","value":"Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic"}],"references":[{"sourceId":"s28-ti-ieee91-logic-symbols","relevance":"Defines 2k+1 and contrasts it with =1."},{"sourceId":"pub-electronics-ti-ls280","relevance":"Manufacturer parity generator and checker documentation."}],"related":["parity-generator-checker","iec-even-parity-element","iec-xor-gate"],"artwork":"s28-iec-odd-parity-element","publishedOn":"2026-10-28","updatedOn":"2026-10-28","provenance":"independent-public-research","symbolVariant":{"convention":"IEC","form":"Rectangular element with the 2k+1 general qualifier","reference":"Qualifying-symbol and dependency conventions as explained in TI's public overview of IEEE Std 91-1984, which incorporates IEC 617-12 work. Independent educational drawing; not certified IEC geometry or an IEC database identifier. The counterpart is the matching functional concept; no equivalence of every detailed standard graphic is asserted.","counterpart":"parity-generator-checker"},"plainEnglish":{"title":"What does IEC odd-parity element mean?","introduction":"The 2k+1 additional drawing mark means the output is active when an odd number of inputs are active. It is what a cascade of two-input exclusive-OR gates actually computes, and it is the correct IEC additional drawing mark for an odd-parity tree drawn as a single element.","example":"Drafters converting older drawings sometimes mark a multi-input parity tree as =1. That is wrong under the IEC meaning, because =1 requires exactly one active input. Replacing it with 2k+1 removes the ambiguity.","drawings":"The element does not indicate the number of data bits on its own; show the full input set or a grouped bus with its width.","terms":[{"name":"Signal","meaning":"Electrical information passed between devices, rather than necessarily the main power supply."},{"name":"Schematic","meaning":"A drawing showing function and connections rather than physical appearance."}],"diagram":"flow","steps":["Identify the device and form","Read the connections and state","Check the equipment reference"],"caption":"A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.","sources":[{"label":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf"},{"label":"SN74LS280 — odd/even parity generation and checking","url":"https://www.ti.com/product/SN74LS280"}],"detail":"Element marked 2k+1 that is active when an odd number of inputs are active, as used for parity. The =1 element gives the same result only for two inputs.","profileId":"reviewed-symbol-20261028"},"url":"https://eloragrid.ai/symbols/iec-odd-parity-element","illustration":{"url":"https://eloragrid.ai/tools/electrical-library/illustrations/iec-odd-parity-element.svg","scope":"Original educational concept; not an official standard graphic or product footprint","license":"https://creativecommons.org/licenses/by/4.0/"},"sources":[{"id":"s28-ti-ieee91-logic-symbols","title":"Overview of IEEE Standard 91-1984: explanation of logic symbols (SDYZ001A)","publisher":"Texas Instruments","url":"https://www.ti.com/lit/ml/sdyz001a/sdyz001a.pdf","type":"manufacturer","scope":"Public explanation of rectangular logic symbols, general qualifiers, input and output qualifiers, dependency notation, bistable elements and coders, consistent with IEC 617-12 work.","checkedOn":"2026-10-28","reuse":"link-only","relevance":"Defines 2k+1 and contrasts it with =1."},{"id":"pub-electronics-ti-ls280","title":"SN74LS280 — odd/even parity generation and checking","publisher":"Texas Instruments","url":"https://www.ti.com/product/SN74LS280","type":"manufacturer","scope":"Public device-function and terminal documentation used as an example of odd/even parity generation and checking. Example part numbers are manufacturer identifiers, not IEC/IEEE symbol IDs. Device ratings, pin numbering and availability remain in the selected product documentation.","checkedOn":"2026-10-14","reuse":"link-only","relevance":"Manufacturer parity generator and checker documentation."}]}