You could use the Rating Stars. As long as you view your files using the detail view.
Right click the file, go to Properties, Details, Rating - click on the stars, perhaps 5 stars = obsolete.
In the Open box (both SW and Windows Explorer) Right click on Name at the top of the column, go down to More, scroll to Rating, check box. Rating appears as a new column, as long as you're using the detail view.
This could become part of your Obsolete procedures.
There is a way of changing folder icons. See below.
Sylvia
Cupertino-JP
Cupertino-JP replied on April 8, 2010See post history
Hi. I believe the problem is that you are in "Documents Library" view, rather than the actual "Folder Location"
1. Right-click the folder you want to change the icon of
2. Select "Open Folder Location"... it's just above "properties"
3. Once you are in the "Folder Location", right-click the folder again that you want to change
4. Select "Properties" at the bottom
5. Select "Customize"... the far right tab
6. the "Change Icon" button is at the bottom
[Note: For the changed icon to show up in the "Library" view also, you may need to close and re-open file explorer]
Hope this helps.