UseLongFileNames Property
True if long file names are used when you save the document as a Web page. False if long file names are not used and the DOS file name format (8.3) is used. The default value is True. Read/write Boolean.
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