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RESO 2023 Summer Developers Workshop

Developers and technology executives: create new technical standards with your peers by attending the RESO 2023 Summer Developers Workshop. Join virtually or in person in Berkeley, California from July 31 to August 1. | LEARN MORE 

Transportation and lodging is your responsibility, but there is no additional registration cost.

Developers and technology executives: create new technical standards with your peers by attending the RESO 2023 Summer Developers Workshop. Join virtually or in person in Berkeley, California from July 31 to August 1.

Registration Open for RESO 2023 Fall Conference

Registration is open for the RESO 2023 Fall Conference. Join us at Paradise Point Resort & Spa in San Diego, California, October 24–26 with an opening reception on October 23.

We are gearing up for another full line-up of speakers and events. Hotel information is provided in the registration confirmation.

For this conference, all indications point to the host hotel selling out, so sign up sooner than later! | REGISTER

Join us at Paradise Point Resort & Spa in San Diego, California, October 24–26 with an opening reception on October 23.

International News

RESO is growing across international borders, as new technology systems based on RESO standards are being developed in the Caribbean, Central and South America, Europe, and West Asia.

RESO began in the United States, but there has long been Canadian consultation in our proceedings. Notable individual contributors helped shape the standards from the very beginning. Organizations like Ontario’s Municipal Property Assessment Corporation (MPAC) and the Canadian Real Estate Association (CREA) helped create unique identifiers, the RESO Common Format and a French-Canadian translation of the RESO Data Dictionary.

We are proud of the many Canadian companies that are part of the RESO fold:

Canadian companies that are part of the RESO fold

Later in this newsletter, you will hear more about how RESO joined 28 real estate boards in Ontario for a meeting to discuss province-wide data sharing.

Czech Republic
Igluu, based in Prague, is building a software system using the RESO Data Dictionary for a new MLS in the Czech Republic. The initiative is a joint venture with ČSOB Bank, a wholly owned subsidiary of KBC Bank based in Belgium. Igluu is a sister company of longtime RESO member Stratus, which builds technology for the Toronto Regional Real Estate Board. | READ MORE

Mexico, Central America and South America
Omni MLS licenses, develops and delivers technology products that seek to improve productivity, profitability and the lives of 100,000 real estate professionals in Latin America, providing tech-forward services built upon RESO standards that ultimately help serve sellers and buyers.

The proof of RESO’s impact on business technology is now clear to the world. International businesses need international technology standards.

RESO Members Building Globally

Product Updates

Data Dictionary
Two new subgroups, Fast Track and Building, are forming under the Data Dictionary Workgroup.

Fast Track Subgroup
The release of Data Dictionary 2.0 will bring new tests on enumerations. The self-testing system will allow data providers to make suggestions for additions or changes to the Data Dictionary. The workgroup is proposing a new model to fast-track the release of high-priority changes without having to wait for major dictionary version changes that could take a year or more to ratify.

This subgroup would create the process to release those changes into the Data Dictionary at a quicker pace. If you would like to participate, please email

Building Subgroup
A proposal initiated by the Real Estate Board of New York (REBNY) suggests that a new resource called Building should be added to the Data Dictionary. The goal is a more accurate description of vertical residential properties. Property features for a building can be different from those of a unit. For example, in a rental listing, the building allows dogs, but the condo owner does not.

Metadata has been collected from several providers, including REBNY’s Residential Listing Service (RLS), and will be aligned with the Data Dictionary to identify candidate fields for a new resource.

Please comment on this post if you are interested in helping to shape the fields of a potential Building Resource.

RESO Analytics: Archiving Certification Endorsements

RESO Analytics
Archiving Certification Endorsements: Providers may now archive endorsements and should do so for any organizations that they are no longer serving or contain results that are otherwise unwanted.

Archiving is available for endorsements in Passed, Notified, Certified, Canceled or Withdrawn status and is performed by selecting the status button for the endorsement to be archived and then selecting Archive.

Auto-Archiving Certification Endorsements: Endorsements in the statuses of Passed, Notified, Canceled or Withdrawn are automatically archived and replaced if a new endorsement of the same type is submitted by the provider. A new Performance Report will also be generated for any endorsement that is auto-archived and replaced. Endorsements in the Certified and Revoked status are not archived and replaced.

Multiple Statuses of Endorsements: Providers are able to retain existing endorsements that are in a permanent status (Certified, Revoked) alongside new in-progress endorsements of the same type.RESO Analytics: Multiple Statuses of Endorsements

RESO Analytics: Sort Options ImprovedProvider System Names: Provider system names have been added to certification reports. Providers may offer more than one system, and the addition of the name allows them to be distinguished from one another. System names have been added to the following reports: Data Dictionary and Web API Reports, Certification Summary Report, and Performance Report. Providers that would like to change their system name may reach out to, and it will be updated by RESO staff.

Sort Options Improved: The name and time sort on the endorsements page has been streamlined to a single menu, requiring fewer clicks.

Improved Clipboard Functionality: The page header bar, endorsements and summary pages allow for copying an organization’s Unique Organization Identifier (UOI) by selecting the clipboard icon.

RESO Analytics: Improved Clipboard Functionality

Certification Update

Congratulations to the following organizations for achieving their Data Dictionary 1.7 and/or Web API Core 2.0.0 endorsements and being added to RESO Analytics:

June 2023 Certification Data Dictionary 1.7 and/or Web API Core 2.0.0 endorsements

View the certification status of all MLSs on the RESO Certification Map. Please send any address or subscriber count changes to

Questions about RESO certification should be directed to your MLS vendor. Questions about self-testing or the technical aspects of certification, may be directed to

In Memoriam

Rick Trevino

Rick Trevino
The RESO community was saddened to hear of the passing of long-time supporter, Rick Trevino. Rick served as chair of the RESO Payloads Workgroup for many years and was a charter member of RESO from his post at MetroList. RESO mourns the loss of this great professional and friend.

Frank Major

Frank Major
We were heartbroken to learn of the passing of Frank Major. Frank served faithfully on the RESO Board of Directors as the CTO of Bright MLS and was a light of leadership, integrity and friendship to all around him. We are grateful for his contributions not only to our organization but to the organized real estate industry.

New Members

RESO New June 2023 Members: Ember, Igluu and

Ember helps buyers find vacation homes through co-ownership and then manages details such as purchasing a fractional share of the home, designing and furnishing it, landscaping and property management.

Igluu, based in Prague, provides a variety of services for real estate practitioners and their clients in the Czech Republic, including a package of ​​services for clients represented by a real estate agent, a CRM and transaction management system for practitioners, and a modern MLS system enabling faster transactions through the standardization of rules and quality data. serves the Maryland area. Their business model is built around technological efficiencies, like having no physical office locations, and an eye toward the future.

Welcome to RESO!


Information Technology Systems Ontario (ITSO)Boards of Canada
RESO joined 28 real estate boards in Ontario, Canada, for a meeting to discuss province-wide data sharing. The meeting was hosted by Information Technology Systems Ontario (ITSO), which manages MLS listing content for 18 member boards and associations in Ontario while providing access to data sharing for 24 of the province’s 34 boards. RESO presented technology opportunities for data accuracy and transparency through certification and alignment reports to support any data collaboration efforts that these groups undertake.

2023 REALTORS® Legislative Meetings
RESO exhibited on the expo floor on May 8–9 during the 2023 REALTORS® Legislative Meetings in Washington, DC, where we promoted RESO membership, RESO Analytics and how to obtain the RED-B designation.

Away from the expo floor, a relevant-to-RESO topic of conversation was the National Association of REALTORS® (NAR) MLS statewide data share initiative, which moved forward as policy in 2023.

While the policy is merely a recommendation, not a mandate, it is a powerful step forward in the effort to deduplicate data listed in multiple sources.

An MLS “statewide data share” is defined as follows:

A statewide data share should deliver MLS data through a common technology interface (e.g., API) of all data fields, including offers of compensation, to all Participants of MLSs in the statewide data share. However, the data should not include MLS-only data fields that are viewable only to the listing Participant and the respective local MLS.

Note: Considerations should be given to:

  • Inclusion of local data fields (non-RESO Standard fields).
  • Any different compensation models such as a percentage of the net vs. gross sales price, tiered commission arrangements and other models that are used by Participants in MLSs.
  • Individual MLS’s “attached document” retention policies and state laws regarding the sharing and retention of documents related to a previous transaction (privacy laws).

On the RESO Blog

RESO Web API Transition Guide

Web API Transition Guide
Transitioning your customer base from the Real Estate Transaction Standard (RETS) to a certified RESO Web API service requires significant planning and communication. To provide a path forward, RESO collaborated with MLS organizations that have already converted their customers to Web API to offer a best practices guide. Mathew Kallumadil from Stellar MLS and Kim Everett from the Western Arizona REALTOR® Data Exchange (WARDEX) represent two MLSs that have fully converted to the RESO Web API, and they spoke about their experiences at the RESO 2023 Spring Conference. | READ MORE



RESO's Working with Real Estate Data - Business Module logoRESO’s Working with Real Estate Data (wwRED) course was created to address the difficulties that new entrants into the industry have with understanding who controls the data and how to access it. The wwRED course and accompanying RED-B designation has met the challenge with industry veterans and newcomers alike.

Listen to what your industry peers are saying about wwRED!

Jeff Young | COO | Realtors Property Resource“The MLS industry is very complex. This is a clear and concise course to educate new employees entering the real estate tech space as well as a valuable refresher for veterans. RPR will be providing the Working with Real Estate Data course as part of our onboarding process for all future hires.”

– Jeff Young | COO | Realtors Property Resource

Richard Gibbens | Executive Director | Southwest MLS“This course is required for all of my existing annual employees and is strongly recommended for all of my volunteer leaders. As a matter of fact, my last three presidents have all taken it and have all loved it. I also find myself talking about it pretty often when I talk to vendors as well – those existing already in the industry and especially the new ones trying to break into the industry.”

– Richard Gibbens | Executive Director | Southwest MLS


Along these same educational lines, a new podcast called the Proptech Pioneers Podcast, hosted by RESO member Evan Knowles, Founder and CEO of Symba, brings startups and MLSs closer together by exploring the beauty and struggle of real estate data and technology.

In the episode with RESO member Hayden Rieveschl, CEO and Founder of Ocusell, the educational benefits of RESO receive heavy praise beginning at 38:04 and lasts for two minutes. As far as we’re concerned, it’s required listening.

Industry News

Latest from CMLS has joined the Arizona Regional Multiple Listing Service (ARMLS) and Metro MLS in Milwaukee in partnership with Markt to launch a new statistics program called RapidStats.

Georgia MLS launches the first phase of AI automation with property image tagging by, creating the ability to automatically detect the room type/home space of all uploaded property images (e.g., bedroom, bathroom, floor plans, etc.) in a RESO-standardized manner.

iOi (Innovation. Opportunity. Investment.) SummitLatest from NAR: iOi in August
Join real estate technology experts at the 5th annual iOi (Innovation. Opportunity. Investment.) Summit in Miami, Florida, August 29–30, to help you uncover proptech solutions to sustain your business and feed your curiosity. Use the promo code “RESO,” to receive $150 off registration costs.

More than 700 leaders, investors and forward-thinking real estate professionals come together for two days to fuel the future of the real estate industry. Proptech is driving transformation, and iOi has become the gathering point for all-hands, frank discussions about innovations that seek to tackle the biggest issues of the industry. | MORE INFO | REGISTER

iOi (Innovation. Opportunity. Investment.) Summit

Three Questions

Three Questions with G. SaxThe Three Questions interview series introduces you to real estate professionals with a hint of personality and humor. 

Here’s who has been interviewed since the last RESO Monthly:



RESO Workgroup Meetings

Commercial Real Estate (CRE) Subgroup | April 5, 2023
The workgroup was presented with the reorganized CRE Mapping Sheet and went through each field to determine which ones were needed for a CRE standard. | NOTES

Transport Workgroup | May 1, 2023
The Transport Workgroup reviewed the upcoming changes to DD 2.0 as well as the new provider/staff review process for local data elements. The group voted to keep working on the Single Feed specification (RCP-035) to include things like conditional field requirements. Business rule requirements were reviewed as well as the existing specification for Validation Expressions in the Web API (RCP-019). | NOTES

Internet Tracking Workgroup | May 17, 2023
The group discussed its role in the RESO architecture and went over several potential changes to the Summary Fields from the Tracking Fields 2.0.10 Specification, including replacing the misleading word, “Total,” standardizing pluralization, PascalCase adherence and adding a specific field for tracking web views that makes sense alongside the same field for mobile views. In the group’s regular privacy update, the latest state-level privacy legislation was discussed along with news of Australia banning TikTok and Italy temporarily suspending ChatGPT. | NOTES

Data Dictionary Workgroup | May 18, 2023
The meeting included a preview of what’s coming in Data Dictionary 2.0, including more strict testing rules and self-testing capability for data providers. New resources and fields will be implemented to facilitate internationalization, expression of local data elements and modeling of “data shapes.” The group plans to vote on the ImageContains field and a direction for Co-Ownership as a PropertyType at the next meeting. The topics of Closet Type to Determine Bedroom Type, Safety Recommendations and FrontageType vs. WaterfrontFeatures were briefly touched on and will also be discussed further at the next meeting. | NOTES

Certification Subgroup | May 18, 2023
The group reviewed the status of the upcoming Data Dictionary 2.0 and Web API Core testing tools and RESO Certification user interface (UI). A community preview of the Data Dictionary 2.0 Preflight Check and the RESO Certification UI will be released soon. The testing rules for RESO Common Format and updated testing rules for the Model, Field and Lookup resources were also discussed. | NOTES

Universal Property Identifier (UPI) Workgroup | May 24, 2023
The group covered the County Metadata Proposal, which may address the nonstandardized identifiers that governing bodies offer as the Assessor’s Parcel Number (APN). A guest from CoreLogic spoke about the nonstandard identifiers they see used as APNs when consuming data and the plan to provide a sample of that to the group. The removal of formatting characters in creating UPIs and the solution of adding a Uniform Resource Name (URN) was revisited. The concept of property-centric vs. listing-centric data as it relates to UPI was described for the group. Additionally, UPI versioning and the ease of UPI adopters transitioning from the first version of UPI to the next was discussed. | NOTES

Rental Subgroup | May 25, 2023
The meeting included a review of all of the StandardStatus lookup definitions and whether they are sufficient for rental listing transactions. The group determined that they should recommend an addition of “all parties have signed and fully executed the lease agreement” (verbiage may be altered) to the Closed status. The recommendation will go to the Standard Status Definitions Subgroup. | NOTES

Upcoming RESO Workgroup Meetings

If you want to participate in any of the following recurring workgroup or subgroup meetings, email to get started.

  • Monday, June 12: Transport Workgroup
  • Tuesday, June 13: Interoperability Workgroup
  • Thursday, June 15: Data Dictionary Workgroup
  • Thursday, June 15: Certification Subgroup
  • Tuesday, June 20: Standard Status Definitions Subgroup
  • Thursday, June 22: Broker Advisory Workgroup
  • Tuesday, June 27: Distributed Ledger Workgroup
  • Wednesday, June 28: Universal Property Identifier (UPI) Workgroup
  • Thursday, June 29: Rental Subgroup
  • Thursday, July 6: Research & Development Workgroup
  • Friday, July 7: Board Liaison Committee
  • Monday, July 10: Transport Workgroup
  • Tuesday, July 11: Interoperability Workgroup
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