- 1995 Sept https://web.archive.org/web/19990202141025/http://home.mcom.... Netscape Navigator 2.0a2 release notes including rollout of TARGET.
- 1995 Sept https://lists.w3.org/Archives/Public/www-html/1995Sep/0034.h... First definition of them; spec text provided by "the Netscape Navigator marketing guy".
- 1997 Jan https://www.w3.org/TR/2018/SPSD-html32-20180315/ HTML 3.2 published without frame target names specced.
- 1997 Aug https://lists.w3.org/Archives/Public/www-html/1997Aug/0010.h... Roles of these target names clarified
- 1997 Dec https://www.w3.org/TR/html401/types.html#h-6.16 HTML 4.0 published with target names.
I can't find any discussion about the choice of character. My guess is that discussion was internal to Netscape as they shipped _then_ specced link target names.