PTT for Android does not support the viewing of file types such as
.doc
(Microsoft Word) or
.ppt
(Microsoft PowerPoint). For the file types listed below, a viewer application is required to view the file content:
application/msword
for Microsoft Word
application/vndopenxmlformats-officedocument.presentationml.presentation
for Microsoft PowerPoint
text/csv
for comma-separated value files
application/vnd.ms-excel
for Microsoft Excel