[Joseph LundersCustomer]

Thanks for the suggestion, I have tried it but unfortunately it is still not working: I have tried isolating the file types…

DXF:
application/dxf, image/vnd.dxf, image/x-dxf
Notes: doesn’t work

DWG:
application/acad, application/x-acad, application/autocad_dwg, image/vnd.dwg, image/x-dwg, application/x-dwg, application/x-autocad, image/x-autocad, drawing/dwg, drawing/x-dwg
Notes: doesn’t work

Revit:
application/octet-stream, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet, application/vnd.ms-excel.sheet.binary.macroenabled.12, application/vnd.ms-excel.sheet.macroenabled.12, application/revit
Notes: doesn’t work for RVT files but it does do some Excel Sheets

RFA:
application/octet-stream, application/vnd.revworks.family, application/x-rfa
Notes: doesn’t work

I am ready to call this project a failure as, unless I am missing something crucial, am unable to limit these file-types using you suggestion. Any further help is very much appreciated.

Thank you,
Joseph