Microsoft Visio

• https://en.wikipedia.org/wiki/Microsoft_Visio

VSDX = “OPC/XML drawing” – looks like my new preferred diagramming exchange format. It is at least OOXML-flavoured:

• http://Jochen.Hayek.name/wp/blog-en/2017/01/18/your-docx-or-your-xlsx-file-and-its-modified-timestamp/

Draw.io is able to import and export diagrams as VSDX.