The diagram below depicts the data flow that supports production of web pages and printable (PDF) documents describing Command and Telemetry packet formats, data structures, etc.
The (GUI-based) LCAT utility generates XML files, C include files, and ITOS records. "cat_get" reads the XML files, transliterating them into YAML ("a_cat/lcat.yml"). "cat_y2h" reads this, as well as the C include files, and generates the aforementioned web pages. "cat_y2t" reads the same information, but generates troff(1) files (which "tr_etc" turns into PDF files). "cat_y2d" reads the XML files, generating dot(1) and pic(1) files.
Note: "cat_y2d" emits pic(1) files (generated via dot(1)) to diagram packet context. "cat_y2h" emits (and also uses) pic(1) files (generated via grap(1)) to plot "alg" (algorithm) specifications. "tr_etc" reads all of these, because "cat_y2t" includes references to them in its "*.tr" files.