Putting one Google doc in multiple folders

Have you ever been torn between whether a particular document should go in one folder vs another?  Perhaps you have a doc that should go in your W3 folder but would make just as much sense to go in your  Writing folder.

The good news is that you can put the doc in both folders.  Here's how:

1. Open Google Drive (not Google Docs for this-- Drive is the organizational app).
2. Click on the file to select it (don't actually open it).  You can even select multiple files with Ctrl-click, if desired.
3. Press Shift-Z.
4. You will then be asked where you want to add the file.  This is not the same as Move To.., because you're not moving it. 
5. Note that this does not make a copy of the file.  It's the exact same doc; you can open and edit it from any of its folders.