Glossary

This glossary prioritizes plain language first, then technical precision.

How to use this glossary

Read this page first. It is the semantic reference for terms used across this site.

The FAQ and standards pages stay intentionally plain language and brief. When a term needs precision, this glossary is the source.

Semantic scope

These definitions are written for this site and aligned to published AXIS and EPM meaning.

When a plain-language explanation is used, the intent is clarity, not a change in technical meaning.

AI

Artificial Intelligence. Software methods that can use structured data for tasks like classification, extraction, and pattern detection.

Examples of widely recognized AI tools include:

ChatGPT (OpenAI) - Company: OpenAI
Copilot (Microsoft/GitHub) - Company: Microsoft
Gemini (Google) - Company: Google
Claude (Anthropic) - Company: Anthropic
Grok (xAI) - Company: xAI

AI-Ready Appraisal Data

Structured appraisal data prepared so BI, AI, and generative AI tools can process it with more consistent and predictable outcomes.

In this context, AI-ready means semantics and structure are explicit enough to reduce brittle extraction and reduce model confusion.

Artifacts

Published materials used to define, implement, validate, or demonstrate a standard.

Artifacts can include specifications, schemas, example payloads, conformance rules, test cases, and implementation guidance.

Application-Layer Encryption

Encryption applied to payload content within the manifest/application model, independent of PDF container encryption.

In EPM context, this is how confidential payload content can be protected while staying within PDF/A constraints for the host document.

Further information: EPM Payload Encryption and Compression

AR

Appraisal Report.

In this site, AR usually refers to structured appraisal report data used in exchange workflows.

APR

Appraisal Review.

In this site, APR usually refers to structured appraisal review data used in exchange workflows.

AMC

Appraisal Management Company. A company that coordinates appraisal ordering, panel management, and delivery workflows between lenders and appraisers.

Associated File

A PDF relationship pattern that binds an embedded file to the host document for machine processing.

Further information: Why the PDF Is the Right Home for Structured Appraisal Data

AXIS

Appraisal Exchange and Interoperability Standard. A public semantic foundation and document definition contracts approach for appraisal report and review data across both real property and chattel contexts.

AXIS is an open standard operated through voluntary, open collaboration across stakeholders.

AXIS uses a layered model (primitives, components, entities, forms, report/review definitions, and instances) to keep semantics stable while allowing workflow-specific contracts.

Its governance emphasizes canonical naming, reuse before duplication, and explicit conformance checks such as unknown-field rejection and contract-claim parity.

As AXIS schemas are formalized, they will be published in public GitHub repositories.

Website: axisstandard.org

Base64

A text encoding method that represents binary content using ASCII characters.

Base64 supports transport compatibility, but by itself it does not provide encryption.

AVM

Automated Valuation Model. A model-driven approach to estimating property value using available market, property, and transactional data.

In this context, AVMs are one downstream BI use case that can improve when appraisal data semantics and structure are more consistent.

BI

Business Intelligence. Analysis and reporting workflows that convert structured data into decision support.

In this site, BI can include AI and Generative AI capabilities when they are used to improve analysis, summarization, classification, forecasting, or decision support workflows.

Common BI tools include Microsoft Power BI, Tableau, Qlik, and even spreadsheet-based dashboards in Microsoft Excel or Google Sheets.

Modern BI workflows may also include AI components, such as anomaly detection, forecasting, natural-language querying, or automated narrative summaries.

Closed Standard

A standard with governance, access, or implementation rights controlled by a limited group, often with membership, licensing, or fee-based access to key artifacts or participation.

Conformance

The degree to which a producer, consumer, or artifact satisfies the requirements of a declared standard contract.

Conformance is separate from marketing claims; it is tied to explicit rules.

Conformance Profile

A named set of implementation constraints and processing rules used to claim conformance in a specific deployment context.

Profiles help producers and consumers align on required behavior for exchange.

Consumer

A system or process that reads and processes structured data produced by another system.

In EPM context, a consumer discovers manifests, validates candidates, and processes payloads.

Compression Algorithm

The declared method used to compress payload data so producers and consumers implement compatible decode behavior.

Using explicit algorithm declarations helps avoid interoperability ambiguity.

Contract

In this site, a contract is an explicit, versioned set of rules that defines what data must contain and how systems should interpret and validate it.

AXIS contracts focus on semantic meaning and conformance behavior, while EPM contracts focus on payload packaging, discovery, and processing expectations.

Contract-Ready Data

Data already shaped to explicit contract requirements so producer and consumer systems share the same expectations during exchange.

Contract-ready data improves validation reliability and reduces integration ambiguity.

Contract-Claim Parity

If a system claims conformance to a contract, it must enforce the requirements of that claimed contract.

This prevents selective conformance claims that omit required checks.

Data Fidelity

The degree to which structured meaning remains intact as data moves across systems and workflows.

High data fidelity means consumers can trust that field meaning was preserved, not guessed from layout.

Data in Transit

Data while it is being sent between systems, networks, or organizations.

Data at Rest

Data while it is stored in a file system, database, archive, or backup location.

Deterministic

Behavior that produces the same result every time when given the same input and rules.

Further information: EPM Payload Encryption and Compression

Discovery Fields

A small set of fields used for quick identification of candidate payload manifests before full validation.

In EPM v1.0 this supports fast discovery workflows when a document may contain multiple embedded candidates.

Domain

In this context, a domain is a real-estate or chattel subject area where structured data has its own business meaning, rules, and workflows.

Domains can contain subdomains that represent more specific use cases. Examples include appraisal reporting, appraisal review, sales-related data, and adjacent property or chattel valuation workflows.

In AXIS, domain and subdomain shaping can expand coverage while preserving core semantic intent.

Document Definition Contracts

Formal definitions that specify what a document must contain and how its structured data is organized, named, and validated.

A document definition contract typically identifies required and optional fields, data types, cardinality, constraints, and conformance expectations between producers and consumers.

EPM

Embedded Payload Manifest. A structured envelope embedded in a PDF to carry machine-readable data with the document.

EPM is an open standard operated through voluntary, open collaboration across stakeholders.

Website: epmstandard.org

Further information: Why the PDF Is the Right Home for Structured Appraisal Data

Embedded File

In PDF context, an embedded file is a file object stored inside the PDF container rather than sent as a separate sidecar.

Further information: Why the PDF Is the Right Home for Structured Appraisal Data

Encryption

The process of transforming data so it can only be read by authorized parties.

In EPM workflows, encryption is typically applied at the payload/application layer; see Application-Layer Encryption.

Further information: EPM Payload Encryption and Compression

Envelope

A wrapper object that carries payload content plus metadata describing that content.

EPM is an example of an envelope pattern.

Further information: Payload, Envelope, and Manifest

Extraction

The process of trying to infer structured meaning from visual document layout, text positioning, or rendered output.

Extraction can be useful, but it is typically more brittle than exchanging native machine-readable data.

Further information: Structured Data vs PDF Extraction

Fannie Mae / Freddie Mac

Government-sponsored enterprises that influence appraisal and mortgage data expectations through policy and delivery requirements.

They jointly advanced structured appraisal data through the Uniform Mortgage Data Program (UMDP), including the Uniform Appraisal Dataset (UAD).

Their collateral and mortgage data ecosystem is closely tied to MISMO standards. MISMO states that its standards are "required by most regulators, housing agencies and the GSEs that participate in the industry."

Reference: MISMO About

Current implementation focus is UAD 3.6 and Forms Redesign, with a published mandate timeline moving the industry toward UAD 3.6 submissions.

UAD 3.6 timeline reference: Fannie Mae UAD and Forms Redesign Update (May 5, 2026)

Generative AI

AI systems that generate new content such as text, code, images, or summaries from prompts and training patterns.

In this context, generative AI can assist with drafting, extraction support, and narrative summarization, but outputs still require human review and domain judgment.

Governance

The process and rules by which a standard evolves, including participation, review, versioning, and decision rights.

In this context, governance helps keep semantic intent stable while enabling controlled expansion.

GSE

Government-Sponsored Enterprise. A federally chartered enterprise that supports mortgage market liquidity and sets delivery expectations for certain loan-related data and documents.

Further information: EPM Payload Encryption and Compression

Host Document

The outer file that carries an embedded payload manifest.

In current EPM usage on this site, the host document is typically a PDF.

Further information: Why the PDF Is the Right Home for Structured Appraisal Data

Interoperability

The ability of different systems, teams, and organizations to exchange data and use it consistently.

In practice, interoperability means information can move across tools and workflows without being rekeyed, reinterpreted, or losing meaning.

JSON

JavaScript Object Notation. A text format commonly used to represent structured data.

LLM

Large Language Model. A type of AI model trained on large text datasets to understand and generate language.

In this context, LLMs are commonly used as Generative AI tools for drafting, summarization, extraction support, and question answering over structured or unstructured appraisal-related content.

Lossless Meaning

A state where data meaning is preserved end-to-end across systems, workflows, and transformations.

Lossless meaning improves interoperability and supports more reliable analytics and model outputs.

Lossy

A condition where some information or meaning is lost when data is converted, moved, or interpreted by another system.

In this context, lossy workflows can reduce data fidelity and lead to inaccurate extraction, weaker model results, or incorrect downstream interpretations.

Media Type

A standardized content type identifier used to describe payload format for routing, validation, and processing.

In EPM context, media type metadata helps consumers determine expected payload handling.

Metadata

Data that describes other data, such as format, version, encoding, compression, or encryption details needed for processing.

Manifest

A structured descriptor that identifies and describes a payload, including metadata needed for discovery and processing.

In EPM, the manifest is the wrapper object that carries one payload and its related metadata.

Further information: Payload, Envelope, and Manifest

Machine-Readable Data

Data structured so software can parse, validate, and process it directly without guessing meaning from visual layout.

In this context, machine-readable data supports more reliable interoperability, analytics, and model outcomes.

Further information: Machine-Readable Data

Middleware

Software that maps or brokers data between internal schemas and shared exchange contracts without requiring a full platform rewrite.

In AXIS adoption, middleware is commonly used to connect existing vendor models to AXIS exchange outputs.

MISMO

Mortgage Industry Standards Maintenance Organization. The standards body for mortgage finance and a subsidiary of the Mortgage Bankers Association.

MISMO supports both primary and secondary mortgage market participants, including lenders, servicers, investors, regulators, housing agencies, and GSE-aligned workflows.

MISMO describes its standards process as open and consensus-based, but its operating model includes closed-access elements such as member-only work products and tooling, along with paid certifications and fee-supported participation.

Its business model is supported by membership, certifications, education/events, and the Innovation Investment Fund (a voluntary per-loan funding model).

Licensing and access model note: MISMO also applies terms-of-use controls that differ from many permissive open-license standards. Its website terms include non-commercial use limitations and state that reproduction, distribution, or transmission of copyrighted MISMO materials is not permitted without written permission.

This differs from standards released under broadly permissive open licenses. For example, EPM uses a dual-license model: documentation/specification text under CC BY 4.0, and schema/examples/code artifacts under Apache-2.0. AXIS schema artifacts are licensed under Apache-2.0 with accompanying NOTICE attribution and standard "AS IS" warranty disclaimer terms.

References: MISMO Terms and Conditions; MISMO Innovation Investment Fund

Normative

Requirements or rules that are mandatory for conformance, as opposed to guidance that is explanatory or optional.

In this glossary, normative content defines what producers and consumers must do to claim conformance.

Object

A grouped unit of data that holds related information together under one named structure.

In plain terms, an object is like a labeled container with fields inside it. In AXIS and EPM workflows, objects help keep related data organized so systems can exchange and process it consistently.

Open Source

Software, schemas, and related technical artifacts published under licenses that allow broad use, modification, and redistribution.

In this context, open source means stakeholders can inspect and contribute to technical artifacts used to implement standards.

Open Standard

A standard designed for broad interoperability with publicly available specifications, transparent governance, and implementation pathways that are intended to be widely accessible.

Open standard and open source are related but not identical concepts; a standard can be open without all implementation artifacts being open source.

Payload

The machine-readable content carried inside an envelope or manifest.

In EPM, the payload is carried in payload.content with accompanying metadata such as type and optional schema reference.

Further information: Payload, Envelope, and Manifest

Payload Agnostic

Able to carry different payload types rather than being restricted to one domain schema.

EPM is payload agnostic; AXIS is one payload use case.

Payload Compression

Compression applied to payload content before transport, with metadata indicating how consumers should decompress.

This improves transfer efficiency while preserving deterministic decode behavior.

Further information: EPM Payload Encryption and Compression

PDF/A-3

A PDF archival format that supports embedding associated files, relevant for carrying embedded payload manifests (EPM).

PDF/A-4f

A PDF/A profile based on PDF 2.0 that supports associated files and modern archival exchange patterns.

In this context, PDF/A-4f is relevant for host documents carrying embedded payload manifests (EPM).

Producer

A system or process that creates structured data artifacts for downstream use.

In this site's semantics, a producer generates AXIS-structured content and, when using EPM transport, emits an EPM manifest with payload metadata for consumer processing.

Public Trust

Confidence from the public and industry participants that appraisal-related standards and outputs are transparent, consistent, and reliable.

In this context, public trust is strengthened when standards are clear, open, and supported by predictable data behavior.

RESO

Real Estate Standards Organization. An independent nonprofit standards body for real estate data interoperability.

RESO's primary domain is MLS and property listing interoperability, with standards used across MLS, broker, agent, and consumer technology tools.

RESO publishes open standards such as the Data Dictionary and Web API, and pairs standards with conformance programs.

Its operating model combines standards development, certification, and industry enablement through workgroups.

RESO funding is supported by membership dues across organization classes, certification-related fees for nonmembers, and education/event programs.

Repository

A version-controlled project workspace that stores documentation, schemas, code, and related artifacts.

In this site context, "repository" usually refers to the public project files used to develop and publish AXIS/EPM guidance and supporting materials.

Schema

A formal definition of data structure and rules, such as required fields, value types, and allowed values.

Semantics

The meaning of data elements and values, not just their format.

In practice, semantics ensure that different people and systems interpret the same field the same way across workflows.

Sidecar File

A separate companion file sent alongside a primary document.

Further information: Why the PDF Is the Right Home for Structured Appraisal Data

Structured Data

Information organized in a consistent format so software can validate, analyze, and exchange it reliably.

Further information: Structured Data vs PDF Extraction

Translation Layer

A mapping layer that transforms an internal model to a shared exchange contract and vice versa for receiving systems.

In AXIS workflows, a translation layer is often implemented as middleware.

UCDP

Uniform Collateral Data Portal. A U.S. mortgage industry portal used by lenders to submit appraisal-related collateral data to the GSE pipeline.

In current UAD 3.6 workflows, submissions commonly include bundled appraisal artifacts such as PDF and XML content.

UMDP

Uniform Mortgage Data Program. A program framework used by the GSEs to standardize mortgage-related data submissions, including appraisal-related workflows.

Further information: EPM Payload Encryption and Compression

UAD

Uniform Appraisal Dataset. A standardized data framework used in appraisal reporting contexts.

USPAP

Uniform Standards of Professional Appraisal Practice. The professional standards framework for appraisal practice in the United States, maintained by The Appraisal Foundation.

In this site context, USPAP defines professional expectations for appraisal practice, while AXIS addresses consistent machine-readable data structure for exchange and downstream processing.

Unknown-Field Rejection

A conformance behavior where undeclared fields are treated as non-conformant.

This helps prevent silent drift in structured contracts.

Validation

The process of checking whether exchanged data satisfies declared contract and conformance rules.

Validation supports reliable producer and consumer interoperability claims.

XML

Extensible Markup Language. A structured text format used to represent and exchange hierarchical data.

In appraisal workflows, XML has been used for machine-readable data transport in prior and current UAD implementations.

ZIP File

A compressed archive container that bundles multiple files into one package for transfer.

In appraisal delivery workflows, ZIP packages are often used to transmit a PDF together with companion machine-readable files.

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