Images from chart page come from the LibreOffice Core.
Some definitions come from the Office Open XML.
Known as "ISO/IEC 29500, Third edition, 2012-09-01"
- Part 1: Fundamentals and Markup Language Reference
- Part 2: Open Packaging Conventions
- Part 3: Markup Compatibility and Extensibility
- Part 4: Transitional Migration Features
- PowerPoint Viewer
- DocumentFormat.OpenXml.Presentation Namespace on MSDN
- Open XML SDK 2.5 with Validator
Library of Congress :
- OOXML Format Family -- ISO/IEC 29500 and ECMA 376
- Schemas in W3C XML Schema language and in RELAX NG for the Strict variant of PPTX, etc.