competitor to Bristol Technology. (Microsoft would later also use MainWin to port Windows Media Player and Outlook Express to Unix.) Now well behind schedule, the 3.0 branch was apparently scrapped in favor of 4.0 (that was released for Windows half a year earlier), which used the new MSHTML (Trident) browser engine. A beta of the Solaris version was made available on November 5, 1997, with a final version expected by March 1998. Tod Nielsen, general manager of Microsoft's developer relations group, jokingly declared that he wanted to hold the launch of the browser at the Ripley's Believe It or Not museum in San Francisco due to the skepticism by those who believed the project was vaporware. It was further reported that versions for HP-UX, IBM AIX, and Irix were planned (note that at the time MainWin XDE 3.0 was only available for the "Solaris SPARC 2.51 platform", but MainWin XDE 2.1 was "available on Solaris SPARC 2.51, Solaris Intel 5.5.1, SunOS 4.1.4, Irix 5.3, Irix 6.2, HP UX 10.2 and IBM AIX 4.1.5".) IE 4.0 for Unix on Solaris was released on March 4, 1998. Later that year a version for HP-UX was released. March 5, 1998: Microsoft reached a settlement with Bristol which "provided mutual releases for any claims arising out of the IE Agreement". 1999 IE 5.0 for Unix on Solaris and HP-UX released. 2001 IE 5.0 for Unix Service Pack 1 released for Solaris and HP-UX. Versions There are nine versions officially listed by Microsoft, listed below in bold. It is not known why Microsoft omitted references to the other ones from its official list. 5.0 Readme highlights Notable items from the IE for Unix 5.0 Readme: "Internet Explorer 5 for UNIX supports most of the features and technologies of Internet Explorer for Windows, but also differs in some respects. For example, Internet Explorer for UNIX does not support downloadable ActiveX controls or browsing and organizing your local files and folders within the browser window. Other unsupported features include filters/transitions in CSS, the DHTML Editing component, and HTML Applications (HTAs). [...] Internet Explorer for UNIX offers some features not found on the Windows version as well, such as Emacs-style keyboard shortcuts and external program associations." Microsoft had a newsgroup named "microsoft.public.inetexplorer.unix" on its public news server msnews.microsoft.com "The User Agent String for Internet Explorer 5 is static except for the third field which depends on the Operating