This content was produced by ansible-playbook-grapher using the --renderer mermaid-flowchart option. The SVG output is probably better overall, but it's nice to know that apg can produce Mermaid as well.
--renderer mermaid-flowchart
See Ansible Playbook Grapher
Scalable Vector Graphics = an XML-based open standard of the W3C since 1999. See wp:SVG
