msoFileTypeAllFiles All files.
msoFileTypeBinders Microsoft Binder file (*.obd).
msoFileTypeCalendarItem Calendar item file (*.ics or *.vsc).
msoFileTypeContactItem Contact item file (*.vcf).
msoFileTypeDatabases Database file (*.mdb).
msoFileTypeDataConnectionFiles Data connection file (*.mdf).
msoFileTypeDesignerFiles Visual Basic Active Designer file (*.dsr).
msoFileTypeDocumentImagingFiles Microsoft Document Imaging file (*.mdi).
msoFileTypeExcelWorkbooks Microsoft Excel workbook (*.wbk).
msoFileTypeJournalItem Microsoft Outlook Journal item
msoFileTypeMailItem Mail item file (*.msg).
msoFileTypeNoteItem Microsoft Outlook Note item.
msoFileTypeOfficeFiles Files with any of the following extensions: *.doc, *.xls, *.ppt, *.pps, *.obd, *.mdb, *.mpd, *.dot, *.xlt, *.pot, *.obt, *.htm, or *.html.
msoFileTypeOutlookItems Any Microsoft Outlook item file.
msoFileTypePhotoDrawFiles PhotoDraw item file (*.mix).
msoFileTypePowerPointPresentations PowerPoint presentation file (*.ppt), PowerPoint template file (*.pot), or PowerPoint slide show file (*.pps).
msoFileTypeProjectFiles Project file (*.mpd).
msoFileTypePublisherFiles Microsoft Publisher file (*.pub)
msoFileTypeTaskItem Microsoft Outlook task item.
msoFileTypeTemplates Microsoft PowerPoint template (*.pot), Word template (*.dot), Excel template (*.xlt).
msoFileTypeVisioFiles Microsoft Visio file (*.vsd).
msoFileTypeWebPages HTML file (*.htm or *.html).
msoFileTypeWordDocuments Microsoft Word document file (*.doc).
As you can see, MSO means.......Microsoft.
So, no, PDF and TXT are not elements of msoFileType, and therefore the answer to:
"Can MSOFiletype be used to search for non- MSOffice file types, such as PDF, TXT? etc."
is, no.
That being said, you most certainly can search for PDF and TXT extensions, using FSO.
Gerry