There are certain character restrictions in SharePoint. This applies to SharePoint 2010, SharePoint 2007, SharePoint 2003. This applies to WSS and SharePoint Foundation. You cannot use certain characters because SharePoint is a web application and must follow a certain framework and structure as defined by being accessed via a ‘web site’.
According to KB article 905231, SharePoint has very specific reserved characters that are invalid for use in site names, subsite names, group names, folder names, and document names. This is frequently overlooked by SharePoint users. I would hazard a guess that many end users are not even aware of this information. How could users be aware of this when SharePoint lets users create content that contain these invalid characters? One of the sites that I have recently been working with has invalid characters in all areas. This particular site has sites, groups, folders, and documents that all contain invalid characters. Please ensure that all of your SharePoint users are aware of the following invalid characters:
- Site Names
- Do not use the following: | # { } % & <TAB>" ~ + \ / : * ? " < >
- Do not start a site name, subsite name, or a site group name with an underscore (_) or with the period character.
- I recommend that you do not use an underscore or a period in site names, folder names, and even document names. Underscores are difficult to see when a browser underlines hyperlinks. While it is possible to use periods or underscores, there are caveats:
- Do not use the period character consecutively in the middle of a site name
- Do not use the period character at the end of a site name
- Folder Names and File Names
- Do not use: " # % & * : < > ? \ / { | } ~
- File names cannot be longer than 128 characters
- Do not use the period character consecutively in the middle of a file name. For example, "file..name.docx" is invalid.
- Do not use the period character at the end of a file name
- Do not start a file name with the period character
this post is very usefull thx!