The Filter property returns or specifies the format used when saving a document. For saving documents in formats other than CDR or CMX, use the Document.ExportEx or Document.ExportBitmap methods.
Examples:
The following VBA example saves the current document as a CMX file with a 5K-color thumbnail.
Sub Test()
Dim so As New StructSaveAsOptions
so.Filter = cdrCMX6
so.ThumbnailSize = cdr5KColorThumbnail
ActiveDocument.SaveAs "C:\Temp\File.cmx", so
End Sub