Table (Draft)

Base Table is a draft protocol with Checkpoint B host-neutral implementation, not a released Adapter conformance claim. D-BASE-TABLE-STRUCTURE-0001, C-TABLE-STRUCTURE-0001, M-TABLE-STRUCTURE-0001, the five P-BASE-TABLE* identities, and T-TABLE-STRUCTURE-0001 govern the current slice. React, Vue, and Vue 2 Adapter profile evidence, CLI facade registration, usable runtime previews, and design-language work remain planned under #621 Checkpoint C.

Table carries information that Template anatomy alone cannot express: ordered parts become a two-dimensional topology with coordinates and spans, and authored header keys resolve to relationships between semantic objects. Adapters can project that graph to an accessibility surface without inferring Table behavior from a prototype name, host tree, CSS class, or Web-only attribute.

The information path is:

Maker-authored parts, spans, and header keys
  -> Table Structure topology and header graph
  -> generic A11y semantic-object graph
  -> Adapter-selected host projection
  -> User-observable table relationships

The definition now has a portable Module and Base family plus bounded Web Component host-projection evidence; it does not claim complete Adapter conformance.

Checkpoint B exports exactly these Base identities with matching source and executable evidence:

Every Row contains at least one HeaderCell or Cell. Head, Body, and RowGroup are deliberately absent: no cross-host evidence makes them required portable identities. A Web or native Adapter may use host row-group wrappers without turning those wrappers into Base facts.

Caption, HeaderCell, and Cell content remains App-owned content passed through each part’s single anonymous Template slot. Table Structure does not parse it into records.

Rows and cells use the current host-observable Anatomy order. The first cell in a Row searches from column zero; each later cell starts at the previous placed cell’s exclusive end and uses the first fitting rectangle at or after that cursor. Placement never backfills an earlier hole in a way that reverses authored order. Indices are zero-based; rowSpan and columnSpan are positive safe integers defaulting to one. A span cannot overlap an occupied rectangle or extend beyond the current row count or safe coordinate boundary. Occupancy uses ranges rather than materializing every covered column, so large spans do not allocate in proportion to their numeric magnitude.

A HeaderCell declares a non-empty, same-domain-unique headerKey and headerKind: 'column' | 'row'. A Cell declares an ordered, non-empty set of header keys. A HeaderCell may declare upstream header keys for layered headers, where upstream means the target precedes the source in computed row-major topology; self and later/downstream references are invalid.

Resolution produces opaque same-domain semantic-object references, split into ordered columnHeaders and rowHeaders, while orderedHeaders preserves the authored order across header kinds for host labeling. It supports multiple headers. Missing, empty, duplicate, ambiguous, unprojectable, self, or downstream references produce structural diagnostics; the implementation must not guess a target or manufacture a host ID. Resolution never searches sibling or nested Table domains, so a key absent locally remains a missing target even when another domain contains an equal key.

Insert, removal, and reorder recompute the snapshot from the actual parts. Temporarily invalid structure may stay mounted and report an invalid snapshot, but it clears owned structural roles, coordinates, spans, and relationships; it does not rewrite authored content or emit data-operation signals.

Base Table reuses the draft generic A11y direction and HC-A11Y-0001; it does not introduce HC-TABLE. Table Structure asks for no physical widget, measurement, input, resource, or system service.

The generic A11y path supports opaque semantic-object references and ordered multi-target relationships through the merged #625 prerequisite. The Web Component evidence now verifies one-based ARIA row and column counts, indices, spans, caption naming, and explicit header labels that retain each cell’s authored content. React, Vue, and Vue 2 Table projection tests remain planned; the passing Web Component slice does not imply complete cross-Adapter or assistive-technology conformance.

The external host comparison establishes a shared information shape only:

This matrix does not extend the bounded Web Component assertions into complete Web, UIKit, Windows, or cross-host conformance. Native versus translated materialization remains an Adapter-profile decision backed by executable evidence.

Base Table owns passive structure only. It excludes:

• App data records and Collection membership;
• sorting;
• row or cell selection;
• pagination and virtualization;
• column resize or reorder;
• editing and data fetching;
• keyboard-grid and focus policy;
• form workflow;
• layout-table mode; and
• shadcn or Brutalist styling.

A later Data Table composition may consume the passive structure while composing separately governed data, Collection, selection, pagination, virtualization, editing, and other capabilities.

The host-neutral reference probe and Module/Base tests cover deterministic placement, multiple-header resolution, diagnostics, nearest-domain isolation, authored-fact churn, exact anatomy, passive negative boundaries, generic A11y emission, and projection cleanup. The Web Component Adapter test covers ARIA materialization for counts, indices, spans, caption identity, and content-preserving header identity. The new @proto.ui/module-table-structure and @proto.ui/prototypes-base/table exports remain draft; React, Vue, and Vue 2 Adapter tests remain planned, and this page provides no interactive Table preview yet.

• D-BASE-TABLE-STRUCTURE-0001
• C-TABLE-STRUCTURE-0001
• T-TABLE-STRUCTURE-0001
• Issue 387
• WAI-ARIA table role
• UIKit accessibility data table
• Windows UI Automation Table pattern