Filing Information Returns Electronically (FIRE)
The Internal Revenue Service (IRS) defines standards for electronic data submission of tax form data from form issuers to the IRS.
The IRS system is described at https://www.irs.gov/e-file-providers/filing-information-returns-electronically-fire. The standard is documented in IRS Publication 1220.
This standard is not used for conveying tax form data from issuers to recipients or tax software. However, if you already produce data in the FIRE format, you may find it helpful to compare the FIRE data structure to the FDX format for each form.