I think you have discovered some forgotten historical artifact of Microsoft Office.
I believe that these registry keys belonged to Microsoft Office FrontPage,
a discontinued WYSIWYG HTML editor and website administration tool from
Microsoft, which used Netscape software.
FrontPage was replaced in 2006 by Microsoft Expression Web and SharePoint Designer,
later also discontinued, but apparently Microsoft Office continues to faithfully
install it to this very day.
I can testify that these keys are still present in Office 2019.
They are to be found in all manual uninstall instructions for Office.
If this worries you, feel free to signal it as a bug via the Windows Feedback Hub.
Note:
I have found more traces of Netscape, this time in ASP.NET.
I found on my computer the files
C:\Windows\Microsoft.NET\Framework\v2.0.50727\CONFIG\Browsers\netscape.browser
and
C:\Windows\Microsoft.NET\Framework64\v2.0.50727\CONFIG\Browsers\netscape.browser
.
A ".browser" file is used by ASP.NET to detect the installed
browser type and define its capabilities for displaying Web page content.
This means that ASP.NET, to this day, is still checking if the Netscape
browser is being used (!).
1Very strange that they keep registering these presumably unused keys. If it ain't broke and all that I guess. I was mostly just confused and could find very little information about them (which is odd considering it's been haunting systems for about 13 years). – Sir_Josh – 2019-03-29T18:12:54.987
13Most of these older "why are these here" keys are left in the software not because they are forgotten, but because there is a desire for backwards compatibility. While I doubt there are many people using netscape with office, you never know. – AggrostheWroth – 2019-03-29T21:34:38.390
15Also, I don’t know anything about these specific keys; but it is shocking the amount of garbage files and keys that Windows and Office have to carry around, because some third-party critical Line-Of-Business software that has not been updated in 15 years from a company that went out-of-business 8 years ago, will crash if the garbage key is missing. – Euro Micelli – 2019-03-30T01:14:09.473
3@EuroMicelli There is precedent for gradually removing these old historical artifacts, though. Microsoft removed legacy code for supporting Outlook Express from the Windows 10 Fall Creators Update, which had been kept in Windows Vista, 7, 8, and earlier Windows 10 builds for compatibility with legacy software. – gparyani – 2019-03-30T07:42:30.693
8From the content in the OP I would actually guess that this is an artefact from setting up inline viewers (applets?) for word, excel, and powerpoint for that browser, not related to frontpage. Wouldn't be surprised if it attempted this for other browsers. Probably the idea is, just make registry keys so that it works if they install the browser after office too. – StarWeaver – 2019-03-30T08:02:58.083
9Someone is using this for spacebar heating... – J... – 2019-03-30T12:21:53.317
Small clarification about ASP.NET: The
netscape.browser
isn't used to detect if Netscape Navigator is installer, but rather if a web site built with ASP.NET is serving content to a Netscape Navigator browser client. (ASP.NET is a web platform.) – Eilon – 2019-04-01T00:49:17.667