You can open a file in Firefox via Firefox > New Tab > Open File.
Then you can click the star in the location bar to bookmark the file in the usual way.

I guess there's more elegant ways of doing, however, the following works:

• Locate the file you want to tag in Firefox
• Drag it into the adress line: the line changes to file:///......... followed by the 'complete path and file name, e.g.

 file///E:/business/schedules%20and%20administrative.xls

(note spaces changed to %20). Firefox handles this kind of adresses exactly the same way as any other adress, for instance starting on https://. When executing this adress, Firefox will normally ask you, as in case of a file download, what you would like to do. See Applications panel - Set how Firefox handles different types of files for more on the subject.

• Drag the adress into the bookmarks
• Rightclick on the new entry in the bookmarks for cosmetics, e.g. to rename it &c as appropriate.

Note that Firefox can only open text and HTML files.
Firefox can't handle Spreadsheet files and other files internally, so you can't open them in Firefox.

Okay, thanks to all for the ideas on how to access regular files. I noted when I did this in one case, Mozilla asked what software on my computer I wanted to use for this file (such as Excel for .xls files), and allowed me to check that it would use this for all files. That is a little extra work than IE which knows it inherently, but certainly acceptable.

Unfortunately, I just realized that instead of opening the file as a native application in Windows, it is opened as the native application (Excel) inside of a firefox window. It loads and runs a little slower that way.

Is there a way to just have it open the file in Excel outside of Firefox?

I have a complex structure of Internet Explorer shortcuts, and I like to work with some of them from the bookmarks toolbar. When I tried to import the full list of my shortcuts into Firefox as bookmarkes, in only brought in the first folder of shortcuts, and left all the others behind (that seems to be a bug in Firefox).

That first folder that it did bring in behaves just as it did in Internet Explorer (even thought it is in Firefox). When I dragged it to the Bookmarks Toolbar, it even looks like a Windows folder, using the Windows system color. The other folders I built using Firefox are white on the bookmarkes taskbar. If you hover over it the one that did import, it will expand into its subfolders, unlike the ones built within Firefox. And most importantly, when I click on an excel file in it, it will open the file in its own application, not the file inside of a mozila window and then the application.

I've tried methods to bring in the remaining internet shortcuts with drag and drop, and I never get the full functionality out of the resulting bookmarks.

Are the Mozilla bookmarks stored in a folder on my computer somewhere, where I can just copy and paste my Internet Explorer and regular Windows shortcuts into it?

re ... Are the Mozilla bookmarks stored in a folder on my computer somewhere, where I can just copy and paste my Internet Explorer and regular Windows shortcuts into it? ..., have a look at this article:

Import Bookmarks and other data from Microsoft Edge

This didn't solve the problem because as I reported on 7/5, I've already run this, and it only imported the first folder of bookmarks, and did not transfer the others. I think that is a Mozilla bug in that transfer routine.

I am trying to get off of IE. But I want to use a feature of Internet Explorer (described above) that allows one to easily access files and websites from the bookmarks, and to import my library of those from IE.

tq

I have a complex structure of Internet Explorer shortcuts, ...

The Import Bookmarks from IE menu item 'chokes' when is gets to multiple nested levels of folders in Favorites.

Doing it this way should avoid that issue, while maintaining your folder structure.
In IE:
File > Import/Export - Export to HTML file

then in Firefox:
Bookmarks > Show All Bookmarks -> Import & Backup - Import HTML... = From HTML file

When I tried to export my full array of IE shortcuts, it only put some of them into the HTML file. I think I could bring them all in one folder at a time, but it still isn't giving me the functionality that IE provides. The Internet favorites imported into Mozilla as bookmarks, but the process did not bring in the "regular" Windows shortcuts to files that Internet Explorer supports. So this didn't work.

Back to my previous question: Does Mozilla store its shortcuts in a folder somewhere (as IE does) so that I can just copy and past the IE "favorites" into Mozilla's folder?

IE (Windows) stares all Favorites and Favorite folders as separate file on the hard drive, so 1000 favorites mean 1000 files on the hard drive that each may take one cluster if they aren't stored in the MFT.
This makes it possible to apply all actions that you can use for files like making a shortcut.
Firefox stores all bookmarks in one SQLite database file (places.sqlite), so that isn't possible.

"When I tried to export my full array of IE shortcuts, it only put some of them into the HTML file."

Nothing to do with Firefox, that is "on" IE for doing an export in that manner. Makes sense though, doing an "export in bookmarks.html format" is primarily intended for moving bookmarks from one computer to another (IMO), and including Windows files shortcuts to files on the "exporting" PC won't work on any other PC - the files wouldn't even be on the "importing" PC and if they were the same exact files, the file path would be different (at least the LUA [user] name would probably differ).

Thanks for the explanation of how Mozilla stores its bookmarks. I can see why using this approach would make a direct import of IE favorites impossible.

I seem to be reaching a point where I know that there is no easy way to bring the IE favorites, including those favorites that are actually file shortcuts, into Mozilla. At some point when I was fooling around, I thought I brought a set of both types of links over to Mozilla, and they functioned.. But I was trying so many things at the time that I don't know which ow what I tried worked.

tq