The RESO Data Dictionary is a living reference source meant to standardize MLS data. It is discussed and often updated monthly in the Data Dictionary Workgroup.
Two core assumptions of the dictionary include extensibility, the ability to extend the dictionary with your own local fields, and omissibility, the expectation that everything from the dictionary should not be in your data just because it’s in the dictionary (e.g., ocean view items in a Nebraska MLS).
You are, however, required to locate field name commonality. If your Price field is really a list price, then you must use the Data Dictionary Standard Name of ListPrice as your field name.
This raises an important distinction between Standard Names vs. Display Names (aka labels) in the dictionary. RESO Certification tests against Standard Names, not Display Names.
Standard Names, which are overwhelmingly written in PascalCase (e.g., TaxAnnualAmount, no spaces), are the data field names needed for technical interoperability. Display Names appear as field labels for reports or listing input (e.g., Tax Annual Amount, spaces included). Display Names are your choice but aligning them to Standard Names is recommended.
Read more at the Larson Consulting LLC blog, written by Rob Larson, RESO Data Dictionary Workgroup Chair.