Understanding the Nomenclature of MLS Data Distribution
Data Feeds
Data Distribution
Data Licensing 
Data Payload
Data Feeds:
Data from an MLS to recipients (brokers, agents, and vendors) is provided to them through a “data feed.”
An MLS may have one data feed, or multiple data feeds, each one containing different data fields or content (Payload), and each one with a different Data License Agreement.
Broker participation is determined by two options:
Opt In – None of the authorized data is transmitted without the owner of the listing, the broker, actually giving permission, or “opting in.” (Informed Consent)
Opt Out – All of the authorized data is transmitted without the owner of the listing, the broker, actually giving permission. To have the data eliminated from the feed requires that the broker take an affirmative action to “opt out.” (Uninformed Consent)
You sometimes hear the term “RETS Feed,” which can be misleading to the uninitiated. I consider this term to be the “language” of the feed, and not the data in the feed or what you can do with the data contained in the feed. That is covered in the Data License Agreement.
Data License:
The data license covers what the recipient can and cannot do with the data received in the feed. What can it be used for? Can the recipient redistribute the data? Can the recipient create new or “derivative works” with the data? This is covered in the Data License Agreement. In the real estate industry, we have three basic data license arrangements, each with different restrictions and rules:
IDX – Broker Data Sharing for Advertising
VOW – Broker Data Sharing for Information purposes
Syndication – Brokers sharing data with unlicensed entities such as REALTOR dot com, old Zillow, etc.
