How do you create sqlite help like diagrams / flowcharts?

Question

Which tool can be used to create Sqlite syntax flowcharts diagrams shown on the sqlite website?

For example, a diagram like:

Answer 1

This is a FAQ:

Each diagram is hand-written using the Pikchr diagramming language. These hand-written specifications are converted into SVG and inserted inline in the HTML files as part of the documentation build process.

Many historical versions of the SQLite documentation used a different process for generating the syntax diagrams. The historical process was based on Tcl/Tk and is described at http://wiki.tcl-lang.org/21708. The newer Pikchr-based syntax diagrams first landed on trunk on 2020-09-26.