The first big change with these forms is in the Uniform Loan Application Dataset, or ULAD, for short. This dataset is used to submit your application data to Fannie Mae and Freddie Mac. The GSEs mapped ULAD to MISMO version 3.4. They used 3.4 because the GSEs would have to engage in extensive use of extensions to have used a lower version of MISMO. They also state that you must use ULAD to submit your data to Desktop Underwriter and your Loan Product Advisor if you're using the new, redesigned URLA. The two things need to go together. If you are interested in the data transmission of your application data to the GSE's automated underwriting systems, they did provide ULAD testing cases on their website, which you can find at fanniemae.com or freddiemac.com.