.PPTX File Format – The package

Office Open XML Presentation

A .pptx file is a ZIP archive that follows the Open Packaging Conventions (OPC), Part 2 of ECMA-376 and ISO/IEC 29500. Each ZIP member is a part. A part’s relationships say which other parts it uses, and [Content_Types].xml says what each part is. Word files use the same scheme: see the DOCX package page for the general rules.

The usual parts

PartHolds
[Content_Types].xmlThe media type of every part.
_rels/.relsThe package’s relationships: the main part and the properties.
ppt/presentation.xmlThe presentation: slide order and size.
ppt/_rels/presentation.xml.relsIts relationships to the slides and masters.
ppt/slides/slide1.xmlOne slide each.
ppt/slideLayouts/, ppt/slideMasters/Layouts and masters.
ppt/notesSlides/, ppt/notesMasters/Speaker notes and their master.
ppt/comments/, ppt/commentAuthors.xmlComments and their authors.
ppt/theme/theme1.xmlThemes.
ppt/media/, ppt/embeddings/Pictures, audio, video and embedded files.
ppt/presProps.xml, ppt/viewProps.xml, ppt/tableStyles.xmlPresentation and view settings and table styles.
ppt/vbaProject.binThe macro project.
docProps/core.xml, docProps/app.xml, docProps/custom.xmlDocument properties.
docProps/thumbnail.jpegA small picture of the first slide, when one was saved.

Writers normally use this layout, but other names are allowed, so a reader finds parts through the relationships.

Content types

The main part’s content type tells the kinds of PowerPoint file apart:

ExtensionMain part content type
.pptxapplication/vnd.openxmlformats-officedocument.presentationml.presentation.main+xml
.pptmapplication/vnd.ms-powerpoint.presentation.macroEnabled.main+xml
.ppsxapplication/vnd.openxmlformats-officedocument.presentationml.slideshow.main+xml
.ppsmapplication/vnd.ms-powerpoint.slideshow.macroEnabled.main+xml
.potxapplication/vnd.openxmlformats-officedocument.presentationml.template.main+xml
.potmapplication/vnd.ms-powerpoint.template.macroEnabled.main+xml

Other parts have types of the form application/vnd.openxmlformats-officedocument.presentationml.slide+xml: slide, slideLayout, slideMaster, notesSlide, notesMaster, handoutMaster, comments, commentAuthors, presProps, viewProps, tableStyles.

Relationship types

The types used in presentations, all with the prefix http://schemas.openxmlformats.org/officeDocument/2006/relationships/ unless shown.

TypeFromTo
officeDocumentPackageThe presentation part.
extended-properties, custom-propertiesPackageApplication and custom properties.
http://schemas.openxmlformats.org/package/2006/relationships/metadata/core-propertiesPackageCore properties.
slidePresentationEach slide.
slideMasterPresentation, layoutA slide master.
notesMaster, handoutMasterPresentationThe notes and handout masters.
slideLayoutSlide, masterThe layout a slide is based on.
notesSlideSlideThat slide’s notes.
commentsSlideThat slide’s comments.
themeMasterThe theme.
image, audio, videoSlide and othersMedia; may be external.
hyperlinkSlideA link, usually external.
oleObject, packageSlideAn embedded object or file.
chartSlideA chart.
diagramData and relatedSlideSmartArt data.
http://schemas.microsoft.com/office/2006/relationships/vbaProjectPresentationThe macro project.

A relationship with TargetMode="External" points outside the package. The explorer lists external targets and never fetches them.

Reading a package

  1. Read the ZIP central directory.
  2. Read _rels/.rels and follow the officeDocument relationship.
  3. Check that part’s root element is presentation in the PresentationML namespace.
  4. Read its relationships to find the slides, masters and themes.

A password-protected PowerPoint file is not a ZIP archive: it is a Compound File with an EncryptedPackage stream.