diff --git a/docs/content/drive.md b/docs/content/drive.md
index aa8734f82..362e2f2d1 100644
--- a/docs/content/drive.md
+++ b/docs/content/drive.md
@@ -1699,7 +1699,7 @@ see User rate limit exceeded errors, wait at least 24 hours and retry.
 You can disable server-side copies with `--disable copy` to download
 and upload the files if you prefer.
 
-### Limitations of Google Docs
+### Limitations of Google Docs, Sheets, etc.
 
 Google docs will appear as size -1 in `rclone ls`, `rclone ncdu` etc,
 and as size 0 in anything which uses the VFS layer, e.g. `rclone mount`
@@ -1720,6 +1720,8 @@ correct size and be downloadable. Whether it will work on not depends
 on the application accessing the mount and the OS you are running -
 experiment to find out if it does work for you!
 
+Affected are not only google docs but also google sheets (and probably other types in an internal google format) - the unknown filesize is only a symptom of a deeper problem. Although mount reports those files with the corresponding office-file-extension, they are of in the google internal format (after all, this is a mount, not sync!). If you double click such a file, your installed office (Writer, rsp. Word ...) tries to open it and fails - because it is not in office but in google format. Only when you copy/paste the file it will be converted to the corresponding office-format and you can work locally with it.
+
 ### Duplicated files
 
 Sometimes, for no reason I've been able to track down, drive will