title: Does officer package support old format of PPT files (Window 97-2003)
body: <p>R Officer package is not able to read old PPT files of type Windows Presentation 97-2003. It gives below error.
  simpleError in zip::unzip(zipfile = newfile, exdir = folder): zip error: <code>Cannot open zip file</code>C:\Users\user1\AppData\Local\Temp\RtmpeYD5pQ\file41fc3c39b6.ppt<code>for reading</code> in file <code>zip.c:238</code>></p>
  
  <p>below is the sample code</p>
  
  <pre><code>content &lt;- read_pptx(fileName)
  data &lt;- pptx_summary(content)
  </code></pre>
  
  <p>The content object should return rpptx object.</p>