expression.UseLongFileNames
expression Required. An expression that returns one of the objects in the Applies To list.
Remarks
If you don't use long file names and your document has supporting files, Microsoft Word automatically organizes those files in a separate folder. Otherwise, use the OrganizeInFolder property to determine whether supporting files are organized in a separate folder.
Example
This example disallows the use of long file names as the global default for the application.
Application.DefaultWebOptions.UseLongFileNames = False