* – an arbitrary string of characters. For example, the "abc*" mask stands for any file with the name beginning with the "abc" string: abc.exe, abc1.com, abc2.rar.
? – any single character. For example, the "abc?.exe" mask stands for any file with the name beginning with the "abc" string followed with an arbitrary single character, like abc1.exe. However, the file abc12345.exe will not match the mask.
Observe the following restrictions:
Masks cannot contain the following characters: >, <, \, /, |, ", ;.
It is not recommended to use masks that match the file extensions of SharePoint service files (for example, *.aspx, *.html, *.mht) in the content filtering settings. Deleting SharePoint service files could disrupt the operation of SharePoint.