PPTX
PowerPoint presentations are also zip with XML inside.
Where it came from
PPTX replaced binary .ppt along with the rest of Office 2007's move to Office Open XML (ECMA-376). Like DOCX/XLSX, it made presentation content accessible to third-party tools — previously that required PowerPoint itself.
How it works
Inside: a ZIP where each slide is its own XML file (slide1.xml, slide2.xml…) under ppt/slides, text lives in 〈a:t〉 runs, images are media files linked through relationship files. Themes and slide masters describe appearance.
So extracting all text and images from a PPTX is just walking the archive — exactly what UWC does: slides are parsed server-side, content is returned without installing Office.
Work with PPTX
Extract presentation content — parsing happens on the server, files aren't stored.