{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.mullion","code":"thing-q2031967","url":"https://ver.cy/models/thing/q2031967/","name":"mullion","alternateNames":[],"kind":"thing","status":"published","version":"0.2.0-wave.3","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.BLT"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A vertical bar dividing a window, door or screen into sections, structural in medieval stone tracery and in timber and metal frames, and used in modern curtain walls as the vertical member carrying glazing; mullions are distinguished from transoms, which are horizontal, and from glazing bars, which subdivide panes, and they define the appearance of Gothic, Tudor and modern facades.","purpose":"Let an agent explain what a mullion is and how it differs from transoms and glazing bars, relay its role in historical and modern construction, and help with terminology in architecture, conservation and glazing.","scope":{"in":[],"out":[],"boundaries":[]},"distinguishingFeatures":["Vertical orientation","Structural or decorative","Historical and modern forms","Defines facade rhythm"],"structure":{"bundles":[{"id":"identify","name":"Identify","description":"What a mullion is.","layers":[{"id":"definition","name":"Definition","description":"Definition and distinctions.","findings":[{"id":"definition-finding","name":"Definition","description":"Definition.","questions":[{"text":"What is a mullion, and how does it differ from a transom and a glazing bar?","kind":"definition"},{"text":"Is the element a mullion, a transom, a glazing bar or a column?","kind":"boundary"}]}]},{"id":"kinds","name":"Kinds","description":"Kinds.","findings":[{"id":"kinds-finding","name":"Kinds","description":"Kinds.","questions":[{"text":"What kinds of mullion exist by material and period?","kind":"definition"},{"text":"Which entry fits the specific kind?","kind":"action"}]}]}]},{"id":"design","name":"Design","description":"Design and construction.","layers":[{"id":"structure","name":"Structure","description":"Structural role.","findings":[{"id":"structure-finding","name":"Structure","description":"Structure.","questions":[{"text":"How do mullions carry loads in stone tracery and in curtain walls?","kind":"provenance"},{"text":"Which entry fits curtain wall?","kind":"action"}]}]},{"id":"performance","name":"Performance","description":"Performance.","findings":[{"id":"performance-finding","name":"Performance","description":"Performance.","questions":[{"text":"How do mullions affect thermal, acoustic and weather performance?","kind":"provenance"},{"text":"Which references are standard?","kind":"provenance"}]}]}]},{"id":"history","name":"History","description":"History and style.","layers":[{"id":"gothic","name":"Gothic","description":"Gothic and Tudor.","findings":[{"id":"gothic-finding","name":"Gothic","description":"Gothic.","questions":[{"text":"How did stone mullions and tracery develop in Gothic and Tudor architecture?","kind":"provenance"},{"text":"Which entry fits tracery?","kind":"action"}]}]},{"id":"modern","name":"Modern","description":"Modern facades.","findings":[{"id":"modern-finding","name":"Modern","description":"Modern.","questions":[{"text":"How do mullions shape modern curtain wall facades?","kind":"provenance"},{"text":"Which entry fits modernist architecture?","kind":"action"}]}]}]},{"id":"care","name":"Care","description":"Conservation.","layers":[{"id":"conservation","name":"Conservation","description":"Conservation.","findings":[{"id":"conservation-finding","name":"Conservation","description":"Conservation.","questions":[{"text":"How are historic mullions repaired and conserved?","kind":"provenance"},{"text":"Which entry fits window conservation?","kind":"action"}]}]},{"id":"terms","name":"Terms","description":"Terminology.","findings":[{"id":"terms-finding","name":"Terms","description":"Terms.","questions":[{"text":"How do glazing and architecture trades use the term, and where do usages differ?","kind":"provenance"},{"text":"Which sources are cited?","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Identify mullions and distinguish them from transoms and glazing bars.","Describe the role of mullions in a facade or historic window from drawings and surveys.","Report cracked stone or corroded mullions to the building owner."],"mustNot":["Approve a curtain wall design without checking mullion wind load by a qualified engineer.","Remove or cut a mullion that may be structural without engineering advice.","Alter historic stone mullions in a protected building without consent.","Confuse mullions with transoms in specifications."],"requiresHuman":["Replacing or altering mullions on a protected or occupied building."]},"ethics":{"considerations":["Failed mullions can drop glass onto people below.","Original mullions are part of the character of historic buildings."],"affectedParties":["Occupants","Passers-by","Building owners"]},"owners":{"steward":"The owner of the building; building control approves structural changes.","roles":[],"masterSystems":[]},"relations":[{"target":"Q4817","type":"parent","note":"registry parent class"},{"target":"column","type":"related","note":"in registry terms, a slender vertical member"},{"target":"architectural element","type":"related","note":"of windows and facades"},{"target":"transom","type":"related","note":"the horizontal member"},{"target":"window","type":"related","note":"or a curtain wall"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.mullion","Wikidata: Q2031967 (https://www.wikidata.org/wiki/Q2031967)"]},"properties":{"applicability":"required","items":["Member height:  mm - Measure the vertical extent between the member's end connections.","Face width:  mm - Measure the visible width perpendicular to the member's vertical axis.","Section depth:  mm - Measure the cross-sectional dimension perpendicular to the glazing or screen plane.","Mass per unit length:  kg/m - Determine mass per measured length for the specified material and section."]},"recognition":{"applicability":"required","items":["Vertical divider in a window or facade","Stone, timber, metal or modern systems","Transoms are horizontal; glazing bars subdivide a single pane; a column supports a building","A vertical bar of stone, wood, metal or plastic between window lights or glazing panels."]},"capabilities":{"applicability":"required","items":["explain the element and its role","distinguish from transoms and glazing bars","relay historical and modern forms","help with terminology"]},"hazards":{"applicability":"required","items":["Thermal bridging in metal mullions","Structural failure under wind load","Confusing mullion with transom"]},"interfaces":{"applicability":"required","items":["Building codes for glazing and curtain walls","Heritage conservation guidance for historic windows","Thermal performance standards for frames"]},"context":{"applicability":"required","items":["Dividing and supporting window and facade openings.","stone mullions in Gothic and Tudor windows","timber mullions in casement and sash windows","metal mullions in curtain walls","applied and decorative mullions","mullions in doors and screens"]}},"sources":[{"title":"Wikidata item Q2031967: mullion","url":"https://www.wikidata.org/wiki/Q2031967","note":"identity and sense of the item"},{"title":"Wikipedia: Mullion","url":"https://en.wikipedia.org/wiki/Mullion","note":"general description of the item"}],"openQuestions":["Should curtain wall mullions be a separate entry?","How should glazing standards be linked?","Is the registry parent assignment to column appropriate?"],"resources":{"spec":"/models/things/publications/thing-q2031967/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q2031967/spec.json"],"providers":["Claude"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T22:30:46Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:28+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}