More on invalid file and folder names

I’ve been talking about file name limitations for SharePoint 2010 resources a couple of months ago, focusing on illegal characters and path/url length.

There is, indeed, something more which is related to invalid “patterns”.

Just to give you an example, you cannot use folder names that end with:

  • .files
  • _files
  • -Dateien
  • _fichiers
  • _bestanden
  • _file
  • _archivos
  • -filer
  • _tiedostot
  • _pliki
  • _soubory
  • _elemei
  • _ficheiros
  • _arquivos
  • _dosyalar
  • _datoteke
  • _fitxers
  • _failid
  • _fails
  • _bylos
  • _fajlovi
  • _fitxategiak

Take a look at this post by Jeremy Jameson for further information.

The reason for this behavior is the special handling of the so-called “thicket folders”.

What is a thicket folder?

I’m copying here some glossary terms from MS-GLOS:

thicket: A complex HTML document may be stored as a thicket, which consists of the thicket main file along with a hidden thicket folder containing a thicket manifest and a set of thicket supporting files that together store the referenced content of the document (for example, a Web page or Office Word HTML document that includes graphics, pictures, or other media is a thicket).

thicket folder: A hidden folder containing a thicket manifest and a set of thicket supporting files that together store the referenced content of a complex HTML document (for example, a Web page or Microsoft Word HTML document that includes graphics, pictures, or other media). A thicket folder has a name based on the name of the thicket main file, with a suffix added that is recognized as a thicket folder.

thicket main file: The main file of an HTML document that references contained elements such as graphics, pictures, or other media stored as thicket supporting files in a thicket folder.

thicket manifest: An XML file containing a manifest for the set of thicket supporting files that together store the referenced content of a thicket main file, which by convention is named filelist.xml and is contained in a hidden thicket folder.

thicket supporting file: A file containing a graphic element, a picture, or other media that is referenced by a thicket main file and stored in a thicket folder as part of a thicket.

What is somehow surprising is that SharePoint does not prevent you from creating such a folder. I mean, no error whatsoever. It just renames the offending folder with a trailing underscore!

Why? Maybe just to make OOTB migration easier (automatic rename instead of manual renames beforehand).

Anyway… tricky, isn’t it?

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