"master" and "slave" do actually appear in ATA-2 and ATA-4 specs, at least in the drafts

The article currently says

Master and slave clarification

Although they are in extremely common use, the terms "master" and "slave" do not actually appear in current versions of the ATA specifications. The two devices are simply referred to as "device 0" and "device 1", respectively, in ATA-2 and later.

This doesn't seem to be entirely correct. While most uses of the terms were changed to device 0/1 (compared to ATA-1) and in the drafts of ATA-2 and ATA-4, the following is stated:

3. Definitions, abbreviations, and conventions
3.1 Definitions and Abbreviations
For the purposes of this American National Standard, the following definitions apply.
...
3.1.11 Master: Previous to this standard, Device 0 has also been referred to as the master. Throughout this document the term Device 0 shall be used.
...
3.1.16 Slave: Previous to this standard, Device 1 has also been referred to as the slave. Throughout this document the term Device 1 shall be used.

Working Draft X3T10/0948D -- Information Technology - AT Attachment Interface with Extensions (ATA-2) -- Revision 4c -- March 18, 1996

3 Definitions, abbreviations, and conventions
3.1 Definitions and abbreviations
For the purposes of this American National Standard, the following definitions apply:

3.1.24 master: In ATA-1, Device 0 has also been referred to as the master. Throughout this document the term Device 0 is used.

3.1.34 slave: In ATA-1, Device 1 has also been referred to as the slave. Throughout this document the term Device 1 is used.

Working Draft -- T13 -- 1153D -- Revision 18 -- 19 August 1998 -- Information Technology - AT Attachment with Packet Interface Extension (ATA/ATAPI-4)

...in addition to appearing in those definitions themselves, the terms appear in:

  • Table 5 - Interface signal names and pin assignments in the ATA-2 draft and Table 6 - Interface signal name assignments in the ATA-4 draft
  • the Signal Descriptions section of both drafts as "M/S- (Master/Slave)"
  • the table of contents for ATA-2, in the part referring to the above-mentioned Signal Descriptions section
  • the ATA-4 specification's new pin diagrams (Figure A.5 - SFF 8057 connector and Figure A.6 - SFF 8058 connector)

While it's possible that the final ATA-4 specification (access to the document requires payment) removed all mentions, the fact that mentions were preserved between the ATA-2 and ATA-4 drafts makes it seem highly unlikely that they were absent from the ATA-2 final spec. —Undomelin (talk) 21:32, 15 November 2018 (UTC)

The terms "master" and "slave" were used up to ATA-6 and replaced in ATA-7. The standards are linked in the article which talks about current versions. --Zac67 (talk) 22:12, 15 November 2018 (UTC)
As I said above, the article currently says "The two devices are simply referred to as "device 0" and "device 1", respectively, in ATA-2 and later." —Undomelin (talk) 23:03, 12 December 2018 (UTC)