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+# Demand: Attribute Value Type Catalog
+
+**Status:** inbound demand (un-reviewed)  
+**Date:** 2026-07-30  
+**Source:** citation-evidence Capture UX (consumer)  
+**Related consumer draft:** `citation-evidence/wiki/AttributeValueTypes-proposal.md`  
+**Proposed workplan:** ITC-WP-0013
+
+---
+
+## Demand signal
+
+Consumer **citation-evidence** needs a **closed, versioned catalog of
+attribute value types** for evidence-backed structured capture (key / type /
+value), including:
+
+- `time`, `datetime`
+- `amount` (quantity + currency)
+- `one-of` (single selection from a code list)
+- `some-of` (multi selection from a code list)
+
+plus existing scalars `text`, long text, `date`.
+
+The consumer must not invent a permanent private type system if InfoTechCanon
+is the semantic reference layer for info-tech domains.
+
+---
+
+## Gap vs current canon
+
+`InfoTechCanonDataModel` already defines:
+
+- Attribute, Field, DataElement, Representation, DataType, CodeList, Constraint
+
+But:
+
+- **DataType** is only a one-line stub,
+- **Representation** lists open examples without a closed catalog,
+- there is **no** machine-readable AttributeValueType registry for application
+  forms / capture UIs.
+
+This demand is for a **canonical collection of value types** (and encoding
+rules), not for a new domain entity competing with Attribute/Field.
+
+---
+
+## Proposed placement
+
+**Preferred:** extension or section under **ITC-DATA** (Data Model):
+
+- concept: `AttributeValueType` (or closed `Representation` profile for
+  capture/forms)
+- artifact: markdown standard + YAML catalog under `infospace/`
+- relationships: AttributeValueType → CodeList (for one-of/some-of), → Constraint
+
+**Avoid:** scattering type ids only inside citation-evidence.
+
+---
+
+## Success criteria
+
+1. Closed list of type ids with definitions and wire encodings.
+2. Clear mapping to Representation / CodeList / Constraint.
+3. Consumer citation-evidence can depend on the catalog (copy or generated
+   constants) without forking names.
+4. Processed via Purpose/Demand if required by ITC-WP-0006 before kernel edit.
+
+---
+
+## Non-goals
+
+- Full statistical data type system.
+- UI widget standards (consumer concern).
+- Vendor form-builder schemas (SurveyJS, etc.) as canon.
diff --git a/workplans/ITC-WP-0013-attribute-value-type-catalog.md b/workplans/ITC-WP-0013-attribute-value-type-catalog.md
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+---
+id: ITC-WP-0013
+type: workplan
+title: "Attribute Value Type catalog (Data Model extension)"
+domain: infotech
+repo: info-tech-canon
+status: proposed
+priority: high
+created: "2026-07-30"
+updated: "2026-07-30"
+depends_on_workplans:
+  - ITC-WP-0006
+owner: codex
+spec_refs:
+  - demand/AttributeValueTypes.md
+  - seeds/InfoTechCanonDataModel_RC1_seed.md
+  - ../citation-evidence/wiki/AttributeValueTypes-proposal.md
+---
+
+# ITC-WP-0013 — Attribute Value Type Catalog
+
+## Goal
+
+Turn the demand in `demand/AttributeValueTypes.md` into a **canonical,
+machine-readable catalog of attribute value types** under the Data Model
+(or a tightly coupled standard), so consumers such as citation-evidence share
+stable type ids, encodings, and CodeList cardinality rules.
+
+## Intent
+
+ITC-DATA already owns Attribute / Field / DataType / Representation / CodeList
+but does not close the set of practical value types for structured capture.
+This workplan fills that gap without inventing a parallel “form field”
+universe.
+
+## Tasks
+
+### T01 — Demand intake (PURPOSES)
+
+```task
+id: ITC-WP-0013-T01
+status: todo
+priority: high
+```
+
+Process `demand/AttributeValueTypes.md` under Purpose/Demand (ITC-WP-0006)
+if still required for kernel-adjacent standards; record decision to extend
+ITC-DATA vs new sibling standard.
+
+### T02 — Draft catalog standard
+
+```task
+id: ITC-WP-0013-T02
+status: todo
+priority: high
+depends_on: [T01]
+```
+
+Draft seed standard section or document:
+
+- closed AttributeValueType list (MVP from consumer proposal)
+- wire encoding rules
+- mapping to Representation / CodeList / Constraint
+- out-of-scope rules (email-as-type, etc.)
+
+### T03 — Machine-readable catalog
+
+```task
+id: ITC-WP-0013-T03
+status: todo
+priority: high
+depends_on: [T02]
+```
+
+Add YAML (+ schema) under `infospace/` and register in indexes/validation.
+
+### T04 — Consumer alignment note
+
+```task
+id: ITC-WP-0013-T04
+status: todo
+priority: medium
+depends_on: [T03]
+```
+
+Publish short alignment note for citation-evidence (and future form UIs);
+link from Data Model kernel map.
+
+---
+
+## Out of scope
+
+- Implementing React widgets (citation-evidence CE-WP-0012).
+- Full ISO 11179 tooling.