# 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

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## 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.

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## 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.