SharePoint Invalid Characters for Sites, Folders, and Files

SharePoint has reserved characters invalid for site names, subsite names, group names, folder names, and document names.These are the invalid characters (see also KB article 905231) :

• Site Names
• Following characters are not allowed: | # { } % & " ~ + \ / : * ? " < >
• A site name, subsite name, or a site group name should NOT begin with an underscore (_) or period character.
• Do not use an underscore or a period. Cons: 
• Cannot use the period character consecutively in the middle of a site name
• Cannot 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