DFORMAT - A Program for Typesetting Data Formats.
dformat reads descriptions of data formats and turns them into pic specifications. It's intended for use as yet another troff preprocessor.
Found via https://minnie.tuhs.org/pipermail/tuhs/2022-January/025081.html
Pikchr (pronounced "picture") is a PIC-like markup language for diagrams in technical documentation. Pikchr is designed to be embedded in fenced code blocks of Markdown or similar mechanisms of other documentation markup languages.
Pikchr source code is released under a zero-clause BSD license.