doc-view-unoconv-program

doc-view-unoconv-program is a variable defined in `doc-view.el'.
Its value is

"soffice"

• This variable is an alias for `doc-view-odf->pdf-converter-program'.
• This variable is obsolete since 24.4;
  use `doc-view-odf->pdf-converter-program' instead.
• This variable may be risky if used as a file-local variable.

Documentation:
Program to convert any file type readable by OpenOffice.org to PDF.

Needed for viewing OpenOffice.org (and MS Office) files.

You can customize this variable.