It's in the V7 sources and binaries in the TUHS archives:

% find . -name '*struct*' -print
./bin/struct
./usr/lib/struct
./usr/lib/struct/structure
./usr/man/man1/struct.1
./usr/src/cmd/struct

On Sat, Mar 14, 2020 at 7:31 AM Harald Arnesen <skogtun@gmail.com> wrote:

> Doug McIlroy [14.03.2020 00:31]:
>
> > struct
> >
> > Brenda Baker undertook her Fortan-to-Ratfor converter against the advice
> > of her department head--me. I thought it would likely produce an ad hoc
> > reordering of the orginal, freed of statement numbers, but otherwise no
> > more readable than a properly indented Fortran program. Brenda proved
> > me wrong. She discovered that every Fortran program has a canonically
> > structured form. Programmers preferred the canonicalized form to what
> > they had originally written.
>
> I've been trying to find the source to this. I have lots of old
> spaghetti-Fortran routines from a former job, and I would love to try
> making it somewhat understandable.
> --
> Hilsen Harald
>