The RULE BookI have worked with hundreds of MLSs around the world and been personally involved in over 100 installations and/or conversions and one thing I have discovered over the years is a little-known fact.  MLSs don’t know the business rules that are built into their MLS systems to control their data, member access and overall permissions and MLS vendors have never created a way for you to see them!

When you consider the complexity of our MLS systems today this is both understandable on one level and really inexcusable on another.  Unfortunately, this lack of knowledge usually comes to light when an MLS is considering a conversion to a new system and the MLS staff realizes they have to tell their new vendor all of the little things they have built into their system over the years that they now want the new MLS system to do as well and they realize they don’t have these rules recorded anywhere.

Unless you deal with these types of things on a daily basis you may have no idea what types of business rules I am talking about so here are some examples:

  • Parent/child relationships – This just means that when one piece of data is entered it impacts other data.  For example, when I enter an address the system may automatically limit the subdivisions and schools I see when I go to select a school.
  • If this/then that – You might have fields you don’t even see when entering a listing unless you select another field previously, to prevent inadvertent data entry errors.
  • Data importing/integration such as when membership data is automatically updated from the membership system to the MLS system.
  • Field rules such as in some MLSs where agent members may not modify certain fields such as expiration dates but brokers can.
  • Reasonableness checks such as calculations that check a sales price that deviates by more than 20% of the list price to see if it is correct and present a.   question to the user to confirm it.
  • Regional rules – In some regional MLSs some boards even have rules managing data at the field level that is different from other boards in the same regional.

Tracking MLS technology business rules is important and unfortunately a need not met by most MLS systems. They don’t provide an easy way to see all of the rules and customizations you have implemented on your system, to make data entry easier, to minimize data entry errors or control data access.  Rules that were implemented during the installation and years of subsequent use are nowhere to be found unless you dig through the system manually, which is amazing when you realize how important these rules are.

WAV Group uses survey software, which is much less mission critical, where you can ask and see all of the logic and custom rules we create for customer surveys yet we can’t do the same thing with our MLS systems.  Shouldn’t this be a core feature in systems at the core of our real estate operations? Which brings up three important recommendations to consider doing in your MLS.


  1. Keep track of your business rules – make someone in your MLS responsible for recording your business rules and updating them as changes occur.  This will need to be done for every single user class, property type, status, individual data fields and board if you are in a regional as well as things like syndication rules 3rd party data feeds.  When and if you need them you will be glad to have stayed on top of them.
  2. As your existing vendor to inventory them– If you have years left on a MLS contract ask your vendor to add this functionality to their administrative tool set or to manually inventory them.  Having access to business rules will also keep you from breaking data dependencies in place that you may have forgotten about.
  3. Ask potential vendors for this feature – If you are moving to a new vendor make this a requirement and see if your new vendor has this capability or will commit to tracking all business rules online so you can access them anytime you wish.
  4. Put it in the contract – If you are doing a new contract with a MLS vendor include a provision that in addition to them providing property data for the MLS conversion they also need to provide you with your MLS business rules if and when you decide to move to a new system.  It’s a reasonable request.

Conversions to new systems are never fun because they force people at all levels to learn new ways of doing things they do every day.  Having a clear understanding of the MLS technology business rules controlling your MLS system will go a long way to helping any change you go through happen more smoothly.

WAV Group helps numerous MLSs evaluate and select technology every year.  If you would like more information on our services contact us at or call us at 716-839-4628.