Most of the information you need - including specifications, test files, and walkthroughs - are housed in this portal. In addition to updating your legacy Full File Fixed and XML credit data APIs, you may want to consider the JSON format, which is the format where several core ACRO products are now available (for example, IDScan, MLA, Credit Report, Scores and Attributes, DTEC, ID Report, and others). Finally, you can integrate with individual stand-alone API's available with these other products.
This format is available to all registered users. You can also access video tutorials located in the Resources and Training tab on the Equifax public transformation site.
Please see this API comparison video for more information.