This item is from the Yet Another Enhanced IDE/Fast-ATA/ATA-2 FAQ, by John Wehman and Peter den Haan with numerous contributions by others. (v1.92).
The IDE field has seen a great number of changes since a few years ago. These novelties are commonly known under the names Enhanced IDE (EIDE) and Ultra-ATA. EIDE has caused a lot of confusion since it is merely a marketing program from Western Digital which, in turn, builds on a couple of real standards: ATA-2 and ATAPI. Fast-ATA, launched by Seagate and endorsed by Quantum in response to WD's marketing is similar. It builds on ATA-2 only. Ultra-ATA is a widely supported extension of ATA-2 (and ATA-3) adding high speed DMA modes.