AXIS Layered Definition Executive Summary

Purpose

This document is the top-level formal planning summary for AXIS layered schema, component, and document-definition work.

AXIS is intended to provide a durable, profession-first structured data foundation for appraisal reporting and appraisal review in a changing industry environment that increasingly demands efficiency, interoperability, and reliable machine-readable meaning.

This is not a product pitch. It is the planning surface for a public-facing semantic and workflow-contract model that the profession can adopt with confidence.

Why This Work Matters

The appraisal profession has already moved far beyond the era of reports typed on paper and delivered by mail.

The current environment expects faster workflows, clearer interoperability, better downstream reuse, and more reliable handling of structured information. At the same time, the profession is entering a period of change where the eventual operating landscape is not fully known.

In that environment, one requirement is already clear: structured data is necessary for the profession to progress in a durable way.

AXIS is intended to provide that structured path.

Core Planning Position

The AXIS work is now best understood as a layered definition system.

The current planning direction uses six architecture layers:

  • Level 1: schema primitives plus governed enumerations,
  • Level 2: component definitions for common field associations and reusable structures,
  • Level 3: entity definitions as validator contracts,
  • Level 4: Form DD contracts,
  • Level 5: Report and Review DD contracts,
  • Level 6: report and review workflow instances governed by selected DD versions.

This allows the profession to adopt a durable semantic model without forcing adoption of any one product or runtime.

The first three levels remain workflow-neutral. Levels 4 through 6 carry workflow-specific contract and instance behavior.

DD taxonomy mapping:

  • Form DD is the layer 4 workflow contract artifact.
  • Report DD and Review DD are layer 5 workflow contract artifacts.
  • Report and review instances governed by those DDs operate at layer 6.

AXIS Shared Semantic Foundation

The AXIS shared semantic foundation defines the meaning of appraisal data and the reusable structures built from that data.

At the first three levels, it is responsible for:

  • entities,
  • fields,
  • identifiers,
  • data types,
  • relationships,
  • controlled vocabularies,
  • cardinality,
  • semantic invariants,
  • missing-data semantics,
  • and reusable components such as common grouped field associations.

Its canonical machine-readable identifier is axis.schema.core.

The schema and component foundation should evolve in a disciplined, versioned, and public way so that the profession can trust AXIS as an independent semantic base.

AXIS is also intended to function as a bridge schema: it should reuse or adapt existing standards where practical, but it must define appraisal-specific semantics where external standards do not go far enough.

AXIS Form And Report Definitions

AXIS document definitions define the workflow-facing contracts built on top of the shared semantic foundation.

They are responsible for:

  • required sections,
  • visible-field expectations,
  • section ordering,
  • narrative slots,
  • grouping of governed content,
  • DD-specific requiredness,
  • report and review instance contract rules,
  • and review targeting rules that do not change underlying data meaning.

The first standard document-definition identifiers remain planned as:

  • axis.document.appraisal-report
  • axis.document.appraisal-review

These artifacts should be versioned and governed centrally.

The current planning direction is that a report instance is governed by a Report DD version, while a review instance is governed by a Review DD version and targets a specific appraisal-report version. Review findings should be allowed to target a section, component, or specific field where needed.

Custom document definitions should be allowed, because that flexibility is a necessary feature for the profession. However, custom document definitions must operate within clear guardrails and must not redefine schema meaning.

Document definitions may also express the same governed semantics in JSON, XML, YAML, or other suitable representations without changing what the schema means.

Initial Scope Emphasis

The current initial scope emphasis is on appraisal forms and reporting workflows outside the most Fannie-centered, MISMO-heavy implementation path.

That includes room for broader non-residential and secondary-market reporting patterns where a neutral appraisal model may be especially useful. It does not prevent AXIS from defining its own governed document definitions for familiar 1004-style reporting structures when useful. If compatibility with outside ecosystems is needed, that translation should be handled through separate mapping layers rather than by allowing external standards to define AXIS semantics.

Public And Private Boundary

The current planning direction is that the schema and document definitions can become public artifacts.

That public posture is valuable because it:

  • supports adoption,
  • allows external review and contribution,
  • reduces suspicion that the model is being shaped only by hidden product incentives,
  • and gives the profession room to evolve the standard as needs change.

This does not require every implementation artifact to be public. The public semantic and document-contract layer should remain distinct from any private runtime or service logic.

Relationship To Implementations

The schema and document definitions are not the implementation.

They are the governed artifacts that implementations consume.

That means they may be consumed by validators, generators, review tools, APIs, communication formats, and other downstream implementations.

No single implementation should define the meaning of AXIS.

AXIS can also benefit external validation engines and other downstream consumers by providing a clear and governed semantic and document-contract foundation.

Planning Direction

The immediate planning goals are:

  • refine the shared semantic foundation,
  • define the first reusable components,
  • define the first standard appraisal and appraisal-review DD artifacts,
  • define review-targeting and report/review contract rules,
  • define compatibility and versioning rules,
  • and prepare the layered AXIS model for eventual public-facing governance.