About a week ago, I received an e-mail asking the following:
I found this weird problem in VSTS/Sharepoint 2003. Create any
folder call “my_files” under any of your TFS project.
Now go to your portal page and look for the same folder. It has been
renamed to “My_files_”. Why the heck “_” has been added? Any clue?
It struck me as a bit odd and I wondered if it might be a bug. I sent an e-mail to Yogita on the Team Foundation team, who in turn sent it to Iyaz, who contacted Shawn on the SharePoint team seeking some insight.
The reply we got back is that this is by design in SharePoint due to thickets. Of course. My first reaction was, “WTF is a thicket?” It turns out that I’ve used them before, but wasn’t aware of the name.
A thicket is what you get when you save a file as an HTM that contains content such as graphics. To store this additional content, which can’t exist in the HTM file, the application creates a special linked folder. It names the folder, filename_files. When a thicket is used on a SharePoint site, the folder is always hidden.
If you create a folder that ends with _files or _file, SharePoint tacks on an extra underscore so that it isn’t treated it as part of a thicket and hidden from view.
Special thinks to Yogita, Iyaz, and Shawn for solving that mystery.